Merge pull request #20 from msgflo/greenkeeper/mqtt-2.3.1

Update mqtt to the latest version 🚀

Author: jonnor

package.json

@@ -30,7 +30,7 @@
     "grunt-mocha-test": "^0.13.2",
     "grunt-shell-spawn": "^0.3.1",
     "mocha": "~3.4.0",
-    "mqtt": "^1.4.0"
+    "mqtt": "^2.7.1"
   },
   "keywords": [],
   "bin": {