chore(package): update mocha to version 3.4.0

Author: greenkeeper[bot]

package.json

@@ -29,7 +29,7 @@
     "grunt-contrib-coffee": "^1.0.0",
     "grunt-mocha-test": "^0.13.2",
     "grunt-shell-spawn": "^0.3.1",
-    "mocha": "~3.3.0",
+    "mocha": "~3.4.0",
     "mqtt": "^1.4.0"
   },
   "keywords": [],