Updates to Hacks2010 WordPress theme

* Bug 851269 - user roles for Guest Author and Reviewer
* Authors and Editors can post unfiltered HTML.
* Contributors can view private posts and moderate comments on their own posts.
* Authors can moderate comments on their own posts.
* Bug 737486 - added social sharing widget.
* Bug 786213 - link to more articles.
* Added tabzilla.
* Some general cleanup and security fixes.