82 -  CSS style guide

A proposed style guide to cover CSS code commits to the jQuery projects.  Open to suggestion for rules, this pass is based on the CSS in jQuery Mobile and jQuery UI.

Based off of Issue https://github.com/jquery/contribute.jquery.org/issues/82
I still think the bad examples here are too vague. There are way too many rules being violated to actually provide value for the reader. We should just drop this and only show good CSS.