Twitter Bootstrap theme for Mayan EDMS

Bootstrap theme for Mayan EDMS!

Effectively, the app contains mostly template overrides for the templates in other apps and applies the Bootstrap conventions. A few themes from Bootwatch are included and the default theme used is [Cosmo](http://bootswatch.com/cosmo/) since I thought it worked best and the theme can be set by the BOOTSTRAP_THEME variable in settings.

At the moment it uses, *all* of the bootstrap code base and this can either be removed later or the functionality in Mayan can be replaced with Bootstrap equivalents.

The icon set uses Glyphicons rather than FamFam using a template filter that maps FamFam icons to Glphyicons. It converts one to the other since the FamFam icon is set in core files and I was keen to try and not edit core files.

However, some core files have been edited, but I've made sure that the changes are non-desctructive. There are two cases where widget functions were edited to include an HTML class so that they could be styled but the inline style is left in place — hopefully we can factor out these HTML strings and I'll propose that in a separate pull request. I've added some commented out settings to the settings.py to facilitate turning the bootstrap theme on and these are documented in the docs. To that end, I've updated the docs, it includes how to install the bootstrap themes in the "Customization" section.