chore(package): update mocha to version 4.0.0

Author: greenkeeper[bot]

package.json

@@ -40,7 +40,7 @@
     "karma-sauce-launcher": "1.2.0",
     "karma-sourcemap-loader": "0.3.7",
     "karma-webpack": "2.0.4",
-    "mocha": "3.5.3",
+    "mocha": "4.0.0",
     "phantomjs-prebuilt": "2.1.15",
     "semver": "5.4.1",
     "should": "13.1.0",