chore(package): update mocha to version 6.2.2

Closes #32

Author: greenkeeper[bot]

package.json

@@ -16,7 +16,7 @@
     "amqplib": "^0.5.1",
     "chai": "^4.1.2",
     "coffee-script": "^1.8.0",
-    "mocha": "^5.0.0",
+    "mocha": "^6.2.2",
     "msgflo": "^0.10.0",
     "mqtt": "^2.15.0"
   },