New Branding for Feeds

![screen shot 2013-12-04 at 22 33 41](https://f.cloud.github.com/assets/49038/1679885/ae8179dc-5d5f-11e3-9f79-20a2ac456935.png)

Piggybacking on the guides' CSS. This vastly simplifies things ( no sprockets / asset paths / padrino helpers etc. ) 
In 2 years time when we decide that `docs.cocoapods.org` was really the way to go, it can change.