Squashed commit of the following:

commit 29ace729f9fae7efa03db6a74a40e7c8947cb609
Author: T.J. M <bionicrm@gmail.com>
Date:   Sat Oct 25 18:13:37 2014 -0400

    Add selection mixin documentation

    Explained in Issue #542 and completed in Commit d349a95290c5df99da438e477b24a5ea5e88df9d
Merge branch 'gh-pages' of github.com:Bionicrm/bourbon into gh-pages