Merge pull request #50 from reactive-react/greenkeeper/mocha-4.0.0

Update mocha to the latest version 🚀

Author: jcouyang

package.json

@@ -48,7 +48,7 @@
     "enzyme": "^2.8.2",
     "jest": "^21.0.0",
     "lodash": "^4.0.0",
-    "mocha": "^3.5.3",
+    "mocha": "^4.0.0",
     "most": "^1.2.2",
     "most-subject": "^5.3.0",
     "nightmare": "^2.10.0",