chore(package): update eslint to version 5.15.2

Closes #29

Author: greenkeeper[bot]

package.json

@@ -10,7 +10,7 @@
   },
   "devDependencies": {
     "chai": "^4.0.1",
-    "eslint": "^4.1.1",
+    "eslint": "^5.15.2",
     "eslint-config-democracyos": "^2.0.0",
     "eslint-plugin-mocha": "~4.11.0",
     "mocha": "~3.5.0",