Redesign Documents

This PR tries again to slice off small parts of 33 and my branch I created from 33

The goal is a faster and better review and a mergeable state as fauxton-master is a fast moving target. We merge parts of the branch iteratively and additionally refactor which is easier with small pieces. Smaller chunks also introduce less bugs as they can be tested more easy and the review does not take hours.

The plan: after this branch the select buttons are moving to the header:

![next-step](https://cloud.githubusercontent.com/assets/298166/5047973/9464f568-6c1a-11e4-99a6-b871617793c1.png)

@seanbarclay one note from the changes I made with the help of your awesome guide:

 - it is currently not possible to style keys/values in the prettify-json area with different colors, they both get the same class from the library

I did not add the ability to hide the checkboxes - this is part of the next step where we have the toggle mechanism in the header. It is not a downgrade to the current functionality. I prepared everything so we can just remove the show-select class on a parent container to remove the checkboxes and to adjust the padding.
@michellephung  I readded it to keep it consistent for now: https://github.com/apache/couchdb-fauxton/commit/4694a4e2af151c85e5d4a73c141676ab5930d9e8