Fix: extract text webpack plugin errors

Author: RyanCCollins

package.json

@@ -172,7 +172,7 @@
     "eslint-plugin-jsx-a11y": "^2.2.3",
     "eslint-plugin-react": "^6.8.0",
     "expect-jsx": "^2.6.0",
-    "extract-text-webpack-plugin": "^v2.0.0-beta.3",
+    "extract-text-webpack-plugin": "v2.0.0-beta.4",
     "file-loader": "^0.9.0",
     "html-loader": "^0.4.4",
     "html-webpack-plugin": "^2.7.1",