downgrade mocha

(peerDependencies error in Node v4)

Author: icebob

package.json

@@ -74,7 +74,7 @@
     "karma-webpack": "1.7.0",
     "lodash": "4.14.1",
     "lolex": "1.5.1",
-    "mocha": "3.0.0",
+    "mocha": "2.5.3",
     "mocha-generators": "1.2.0",
     "mocha-loader": "0.7.1",
     "moment": "2.14.1",