Docsite css updates

The main purpose of this change was to remove the imposed 800px max width for the content of the docs.  It should now be fluid.

The secondary purpose is to add a non-minified version of theme.css so that it will be easier to update in the future.

In this pull request theme.css has been minified using yuicompressor.  If having a minified theme.min.css is not really required and we are fine delivering a non-minified css file, then I can yank theme.min.css out.

We could always update build-site.py to have a yuicompressor step or to use something else written in python.