chore(package): update eslint to version 3.1.1

Author: greenkeeperio-bot

package.json

@@ -30,7 +30,7 @@
   },
   "devDependencies": {
     "coveralls": "~2.11.12",
-    "eslint": "~2.11.0",
+    "eslint": "~3.1.1",
     "lodash.assign": "~4.2.0",
     "mocha": "~3.0.2",
     "must": "~0.13.1",