fix(deps): update dependency eslint to ^4.0.0 (#27)

Author: renovate[bot]

package.json

@@ -68,7 +68,7 @@
     "chai": "^4.0.0",
     "codecov": "^3.0.0",
     "copy": "^0.3.0",
-    "eslint": "^3.15.0",
+    "eslint": "^4.0.0",
     "eslint-plugin-flowtype": "^2.30.0",
     "eslint-watch": "^3.0.0",
     "flow-bin": "^0.61.0",