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 think that was actually the intention here but we probably need to split this up into 2 parts like the JS style guide has for the jshint settings. @mikesherov requested it here https://github.com/jquery/contribute.jquery.org/pull/83#issuecomment-46563557