message: chore(package): update mocha to version 4.0.1
  Closes
diff: "babel-preset-es2015": "^6.22.0",
  "babylon": "~6.18.0",
  "esprima-fb": "^15001.1001.0-dev-harmony-fb",
  + "mocha": "~4.0.1",
  "flow-parser": "^0.55.0",
  - "mocha": "~3.5.3",
  "reify": "^0.12.3",
  "semver": "^5.3.0"
  },
  