chore(package): update eslint to version 3.18.0

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -15,7 +15,7 @@
   },
   "devDependencies": {
     "coveralls": "^2.11.16",
-    "eslint": "^3.17.0",
+    "eslint": "^3.18.0",
     "istanbul": "^0.4.5",
     "mocha": "^3.2.0",
     "mocha-lcov-reporter": "^1.2.0",