chore(package): update mocha to version 3.0.0

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -29,7 +29,7 @@
   "devDependencies": {
     "chai": "^3.4.1",
     "coveralls": "^2.11.6",
-    "mocha": "^2.3.4",
+    "mocha": "^3.0.0",
     "nyc": "^7.0.0",
     "rimraf": "^2.5.0",
     "standard": "^7.1.0"