chore(package): update extract-text-webpack-plugin to version 3.0.0

Closes #165

Author: greenkeeper[bot]

package.json

@@ -84,7 +84,7 @@
     "eslint-plugin-jsx-a11y": "^4.0.0",
     "eslint-plugin-react": "^6.7.1",
     "eslint-watch": "^3.0.0",
-    "extract-text-webpack-plugin": "^1.0.1",
+    "extract-text-webpack-plugin": "^3.0.0",
     "fake-style-loader": "^1.0.1",
     "file-loader": "^0.9.0",
     "flow-bin": "^0.42.0",