chore(package): update mocha to version 2.5.3

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -37,7 +37,7 @@
     "babel-plugin-add-module-exports": "^0.1.2",
     "babel-preset-es2015": "^6.1.2",
     "coveralls": "^2.11.8",
-    "mocha": "^2.4.5",
+    "mocha": "^2.5.3",
     "npm-run-all": "^1.5.1",
     "nyc": "^6.0.0",
     "rimraf": "^2.5.2"