Overhaul the docs

This is a major redesign and overhaul of the docs and can be previewed at [http://ascott1.github.io/capital-framework/](http://ascott1.github.io/capital-framework/). This is by no means finished, but I think it's in a state that we can make it "official."


![selfie-0](http://i.imgur.com/NWVVClN.gif)

`.content_wrapper` is used to wrap `.content_main` and `.content_sidebar`. You probably want a `.wrapper__match-content` instead.