chore(package): update eslint to version 6.2.0

Closes #14

Author: greenkeeper[bot]

package.json

@@ -50,7 +50,7 @@
     "chai-as-promised": "^7.1.1",
     "co-mocha": "^1.2.0",
     "coveralls": "^3.0.0",
-    "eslint": "^5.0.0",
+    "eslint": "^6.2.0",
     "istanbul": "^0.4.5",
     "lodash": "^4.17.4",
     "mocha": "^5.0.0"