chore(package): update mocha to version 5.1.1

Closes #41

Author: greenkeeper[bot]

package.json

@@ -49,7 +49,7 @@
     "eslint": "^3.0.0",
     "glob": "^7.0.0",
     "istanbul": "^0.4.1",
-    "mocha": "^3.0.2",
+    "mocha": "^5.1.1",
     "require-directory": "^2.1.1"
   },
   "engines": {