Update eslint to the latest version 🚀 (#150)

* chore(package): update eslint to version 6.0.0

* chore(package): update lockfile package-lock.json

Author: greenkeeper[bot]

package-lock.json

@@ -34,7 +34,7 @@
     "minimist": "1.2.0"
   },
   "devDependencies": {
-    "eslint": "^5.16.0",
+    "eslint": "^6.0.0",
     "istanbul": "^0.4.3",
     "mocha": "^6.1.4",
     "mockery": "^2.1.0",