Update dependency mocha to v5.1.0

Author: renovate-bot

package.json

@@ -32,6 +32,6 @@
     "babel-preset-es2015": "6.24.1",
     "babel-preset-stage-0": "6.24.1",
     "babel-polyfill": "6.26.0",
-    "mocha": "4.0.1"
+    "mocha": "5.1.0"
   }
 }