Use MutationObserver to increase performance

Author: zxdong262

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "pipedrive-embeddable-ringcentral-phone-spa",
-  "version": "2.0.3",
+  "version": "2.0.4",
   "description": "Add RingCentral Embeddable Voice widgets to Pipedrive",
   "keywords": [
     "RingCentral",
@@ -68,7 +68,7 @@
     "react-dom": "^16.13.1",
     "recursive-assign": "0.2.0",
     "replace-in-file": "^5.0.2",
-    "ringcentral-embeddable-extension-common": "0.8.8",
+    "ringcentral-embeddable-extension-common": "0.9.0",
     "shelljs": "0.8.2",
     "standard": "^12.0.1",
     "style-loader": "0.23.1",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "Ringcentral Embeddable Widgets for Pipedrive",
-  "version": "2.0.3",
+  "version": "2.0.4",
   "description": "Add RingCentral Embeddable Voice widgets to Pipedrive",
   "key": "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA1YqYvCEeGGNOgtKrx8DfG33ujx7NgAwbyVpikug4mHiNvKZYWulw7lY5fjaD8wAy5bmXnkfULDzqMkL8UOxUcf8qD2lJFcLm+BqBtqNnoSz00vwjSOxXrcDvpvsMrjEZkI7N/FD60sTWp1U+QOehua7OboUpXb4iV7TQfppz3PsCz7qGOa4PWjUMAZTTgomUtW47Es6f/vjIeejs7Ihro3Al5Jo3SWIbjpjSU9BK34XgFvtcZx3lZQgfFiK+ZNyxlx8mgC/PLqJB+uX63ywMrT86TdcfxBuaThy98S8SCXjZTpHOP6X5pmGMk0lPM06hwxmSCBZgHOHL/Wk6r8FUlQIDAQAB",
   "permissions": [