Merge pull request #3 from grayyang/greenkeeper/mocha-4.0.0

Update mocha to the latest version 🚀

Author: grayyang

package.json

@@ -36,7 +36,7 @@
     "coveralls": "^2.13.1",
     "eslint": "^4.4.1",
     "js-promisify": "^1.1.0",
-    "mocha": "^3.5.0",
+    "mocha": "^4.0.0",
     "nyc": "^11.1.0",
     "rimraf": "^2.6.1",
     "webpack": "^3.5.4",