Add beautified theme.css

* Update theme.conf to use theme.min.css
* Add "beautified" (un-minified) theme.css
Add *.min.css to docsite/.gitignore
Add staticmin make target for compressing docs related css and js files, currently only theme.css
Use some sed magic as the css minifier
Properly indent @media blocks
Get rid of grey background when content doesn't fill the screen
Increase the content max-width to 1140px from 800px
Don't overwrite max-width for wy-nav-content