chore(package): update file-loader to version 4.0.0

Closes #203

Author: greenkeeper[bot]

package.json

@@ -19,7 +19,7 @@
     "ejs-loader": "^0.3.0",
     "eslint": "^4.18.0",
     "extract-text-webpack-plugin": "^3.0.2",
-    "file-loader": "^1.1.6",
+    "file-loader": "^4.0.0",
     "git-prepush-hook": "^1.0.1",
     "html-loader": "^0.5.5",
     "html-webpack-plugin": "^3.0.0",