chore(package): update css-loader to version 0.28.1

Closes #12

https://greenkeeper.io/

Author: greenkeeper[bot]

package.json

@@ -58,7 +58,7 @@
     "babel-preset-es2015": "^6.18.0",
     "babel-preset-react": "^6.16.0",
     "babel-runtime": "^6.20.0",
-    "css-loader": "0.26.1",
+    "css-loader": "0.28.1",
     "extract-text-webpack-plugin": "^1.0.1",
     "file-loader": "0.9.0",
     "git-scripts": "^0.2.1",