chore(package): update mocha to version 4.0.1

Closes #21

Author: greenkeeper[bot]

package.json

@@ -21,7 +21,7 @@
     "amqplib": "^0.5.1",
     "chai": "~4.1.0",
     "coffee-script": "^1.8.0",
-    "mocha": "~3.3.0",
+    "mocha": "~4.0.1",
     "mqtt": "~1.4.0",
     "msgflo": "^0.10.0"
   },