Update css-loader requirement to 0.28.10

Updates the requirements on [css-loader](https://github.com/webpack-contrib/css-loader) to permit the latest version.
- [Release notes](https://github.com/webpack-contrib/css-loader/releases)
- [Changelog](https://github.com/webpack-contrib/css-loader/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack-contrib/css-loader/commits/v0.28.10)

package.json

@@ -29,7 +29,7 @@
     "babel-loader": "6.4.1",
     "babel-polyfill": "6.26.0",
     "babel-preset-env": "1.6.0",
-    "css-loader": "0.27.3",
+    "css-loader": "0.28.10",
     "easygettext": "1.3.0",
     "expose-loader": "0.7.3",
     "jquery": "3.2.1",