chore(package): update mocha to version 3.1.2

https://greenkeeper.io/

package.json

@@ -229,7 +229,7 @@
     "karma-sinon": "1.0.5",
     "karma-sourcemap-loader": "0.3.7",
     "karma-webpack": "1.8.0",
-    "mocha": "3.1.1",
+    "mocha": "3.1.2",
     "node-sass": "3.10.1",
     "po2json": "0.4.5",
     "postcss-loader": "0.13.0",