chore(package): update mocha to version 3.1.0

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -28,7 +28,7 @@
     "ember-publisher": "0.0.7",
     "git-repo-version": "0.4.0",
     "json3": "^3.3.2",
-    "mocha": "^1.20.1",
+    "mocha": "^3.1.0",
     "promises-aplus-tests-phantom": "^2.1.0-revise",
     "release-it": "0.0.10"
   },