chore(package): update eslint to version 4.1.1

Closes #482

Author: greenkeeper[bot]

package.json

@@ -28,7 +28,7 @@
     "babel-preset-env": "^1.2.0",
     "babel-register": "^6.18.0",
     "cross-env": "^5.0.0",
-    "eslint": "^3.8.1",
+    "eslint": "^4.1.1",
     "eslint-config-babel": "^7.0.0",
     "eslint-plugin-flowtype": "^2.25.0",
     "eslint-plugin-prettier": "^2.1.2",