Add support for CSS modules

[dsebastien]

See doc here: https://github.com/css-modules/css-modules

Idea: local css FTW!

• support has been added to webpack's css-loader: https://github.com/webpack/css-loader
  • webpack config example: (notice css-loader?modules...): https://github.com/css-modules/webpack-demo/blob/master/webpack.config.js
• there's a postcss plugin: https://github.com/outpunk/postcss-modules