chore(package): update mocha to version 4.0.1

Closes #33

Author: greenkeeper[bot]

package.json

@@ -69,7 +69,7 @@
     "flow-bin": "^0.43.1",
     "flow-watch": "^1.1.1",
     "istanbul": "^0.4.5",
-    "mocha": "^3.5.3",
+    "mocha": "^4.0.1",
     "nyc": "^11.0.1",
     "pre-commit": "^1.2.2",
     "redux": "^3.6.0",