diff --git a/demo/package-lock.json b/demo/package-lock.json
index 070e850..c7882d3 100644
--- a/demo/package-lock.json
+++ b/demo/package-lock.json
@@ -2787,7 +2787,8 @@
             },
             "ansi-regex": {
               "version": "2.1.1",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "aproba": {
               "version": "1.2.0",
@@ -2805,11 +2806,13 @@
             },
             "balanced-match": {
               "version": "1.0.0",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "brace-expansion": {
               "version": "1.1.11",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "balanced-match": "^1.0.0",
                 "concat-map": "0.0.1"
@@ -2822,15 +2825,18 @@
             },
             "code-point-at": {
               "version": "1.1.0",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "concat-map": {
               "version": "0.0.1",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "console-control-strings": {
               "version": "1.1.0",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "core-util-is": {
               "version": "1.0.2",
@@ -2933,7 +2939,8 @@
             },
             "inherits": {
               "version": "2.0.3",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "ini": {
               "version": "1.3.5",
@@ -2943,6 +2950,7 @@
             "is-fullwidth-code-point": {
               "version": "1.0.0",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "number-is-nan": "^1.0.0"
               }
@@ -2955,17 +2963,20 @@
             "minimatch": {
               "version": "3.0.4",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "brace-expansion": "^1.1.7"
               }
             },
             "minimist": {
               "version": "0.0.8",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "minipass": {
               "version": "2.3.5",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "safe-buffer": "^5.1.2",
                 "yallist": "^3.0.0"
@@ -2982,6 +2993,7 @@
             "mkdirp": {
               "version": "0.5.1",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "minimist": "0.0.8"
               }
@@ -3054,7 +3066,8 @@
             },
             "number-is-nan": {
               "version": "1.0.1",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "object-assign": {
               "version": "4.1.1",
@@ -3064,6 +3077,7 @@
             "once": {
               "version": "1.4.0",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "wrappy": "1"
               }
@@ -3139,7 +3153,8 @@
             },
             "safe-buffer": {
               "version": "5.1.2",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "safer-buffer": {
               "version": "2.1.2",
@@ -3169,6 +3184,7 @@
             "string-width": {
               "version": "1.0.2",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "code-point-at": "^1.0.0",
                 "is-fullwidth-code-point": "^1.0.0",
@@ -3186,6 +3202,7 @@
             "strip-ansi": {
               "version": "3.0.1",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "ansi-regex": "^2.0.0"
               }
@@ -3224,11 +3241,13 @@
             },
             "wrappy": {
               "version": "1.0.2",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "yallist": {
               "version": "3.0.3",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             }
           }
         },
@@ -4840,11 +4859,6 @@
       "resolved": "https://registry.npmjs.org/etag/-/etag-1.8.1.tgz",
       "integrity": "sha1-Qa4u62XvpiJorr/qg6x9eSmbCIc="
     },
-    "eventemitter3": {
-      "version": "3.1.2",
-      "resolved": "https://registry.npmjs.org/eventemitter3/-/eventemitter3-3.1.2.tgz",
-      "integrity": "sha512-tvtQIeLVHjDkJYnzf2dgVMxfuSGJeM/7UCG17TT4EumTfNtF+0nebF/4zWOIkCreAbtNqhGEboB6BWrwqNaw4Q=="
-    },
     "events": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/events/-/events-3.0.0.tgz",
@@ -5845,13 +5859,20 @@
       "integrity": "sha1-ksnBN0w1CF912zWexWzCV8u5P6Q="
     },
     "http-proxy": {
-      "version": "1.17.0",
-      "resolved": "https://registry.npmjs.org/http-proxy/-/http-proxy-1.17.0.tgz",
-      "integrity": "sha512-Taqn+3nNvYRfJ3bGvKfBSRwy1v6eePlm3oc/aWVxZp57DQr5Eq3xhKJi7Z4hZpS8PC3H4qI+Yly5EmFacGuA/g==",
+      "version": "1.18.1",
+      "resolved": "https://registry.npmjs.org/http-proxy/-/http-proxy-1.18.1.tgz",
+      "integrity": "sha512-7mz/721AbnJwIVbnaSv1Cz3Am0ZLT/UBwkC92VlxhXv/k/BBQfM2fXElQNC27BVGr0uwUpplYPQM9LnaBMR5NQ==",
       "requires": {
-        "eventemitter3": "^3.0.0",
+        "eventemitter3": "^4.0.0",
         "follow-redirects": "^1.0.0",
         "requires-port": "^1.0.0"
+      },
+      "dependencies": {
+        "eventemitter3": {
+          "version": "4.0.7",
+          "resolved": "https://registry.npmjs.org/eventemitter3/-/eventemitter3-4.0.7.tgz",
+          "integrity": "sha512-8guHBZCwKnFhYdHr2ysuRWErTwhoN2X8XELRlrRwpmfeY2jjuUN4taQMsULKUVo1K4DvZl+0pgfyoysHxvmvEw=="
+        }
       }
     },
     "http-proxy-middleware": {
@@ -6620,7 +6641,8 @@
             },
             "ansi-regex": {
               "version": "2.1.1",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "aproba": {
               "version": "1.2.0",
@@ -6638,11 +6660,13 @@
             },
             "balanced-match": {
               "version": "1.0.0",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "brace-expansion": {
               "version": "1.1.11",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "balanced-match": "^1.0.0",
                 "concat-map": "0.0.1"
@@ -6655,15 +6679,18 @@
             },
             "code-point-at": {
               "version": "1.1.0",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "concat-map": {
               "version": "0.0.1",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "console-control-strings": {
               "version": "1.1.0",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "core-util-is": {
               "version": "1.0.2",
@@ -6766,7 +6793,8 @@
             },
             "inherits": {
               "version": "2.0.3",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "ini": {
               "version": "1.3.5",
@@ -6776,6 +6804,7 @@
             "is-fullwidth-code-point": {
               "version": "1.0.0",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "number-is-nan": "^1.0.0"
               }
@@ -6788,17 +6817,20 @@
             "minimatch": {
               "version": "3.0.4",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "brace-expansion": "^1.1.7"
               }
             },
             "minimist": {
               "version": "0.0.8",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "minipass": {
               "version": "2.3.5",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "safe-buffer": "^5.1.2",
                 "yallist": "^3.0.0"
@@ -6815,6 +6847,7 @@
             "mkdirp": {
               "version": "0.5.1",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "minimist": "0.0.8"
               }
@@ -6887,7 +6920,8 @@
             },
             "number-is-nan": {
               "version": "1.0.1",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "object-assign": {
               "version": "4.1.1",
@@ -6897,6 +6931,7 @@
             "once": {
               "version": "1.4.0",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "wrappy": "1"
               }
@@ -6972,7 +7007,8 @@
             },
             "safe-buffer": {
               "version": "5.1.2",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "safer-buffer": {
               "version": "2.1.2",
@@ -7002,6 +7038,7 @@
             "string-width": {
               "version": "1.0.2",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "code-point-at": "^1.0.0",
                 "is-fullwidth-code-point": "^1.0.0",
@@ -7019,6 +7056,7 @@
             "strip-ansi": {
               "version": "3.0.1",
               "bundled": true,
+              "optional": true,
               "requires": {
                 "ansi-regex": "^2.0.0"
               }
@@ -7057,11 +7095,13 @@
             },
             "wrappy": {
               "version": "1.0.2",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             },
             "yallist": {
               "version": "3.0.3",
-              "bundled": true
+              "bundled": true,
+              "optional": true
             }
           }
         }