chore(package): update eslint to version 4.0.0

Author: greenkeeper[bot]

package.json

@@ -37,7 +37,7 @@
     "babel-core": "6.25.0",
     "babel-preset-es2015": "6.24.1",
     "del": "3.0.0",
-    "eslint": "3.19.0",
+    "eslint": "4.0.0",
     "eslint-config-google": "0.7.1",
     "gulp": "3.9.1",
     "gulp-babel": "6.1.2",