Add CSS modules support

[jenglamlow]

Hi,

I've updated the webpack config to support CSS modules. I'm not sure whether you want to merge it as a feature, as merging might cause the previous css rendering to fail.

With this implementation, it is required to wrap the css property with :global tag to declare the attribute as global scoped as mentioned here

[vladdancer]

@jenglamlow, Nice! Also I definitely try out this lib https://github.com/css-modules/css-modules