chore(package): update mocha to version 3.0.0

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -20,7 +20,7 @@
     "babelify": "6.4.0",
     "chokidar-cli": "1.1.0",
     "eslint": "3.3.0",
-    "mocha": "2.3.3"
+    "mocha": "3.0.0"
   },
   "scripts": {
     "lint": "eslint src",