Modify "roles" system to better match forums

The forums have been updated so that admins can add arbitrary classes to all of a given user’s posts, allowing for custom mod star-like icons without having to put user IDs directly in the CSS. This makes our remote CSS downloading less useful since we don’t have those custom classes in our templates.

Instead of checking the “.author” DT for specific classes, let’s grab all of that element’s classes so that we automatically get the new classes as admins add them.

Closes #304.
Bump version to 2.0.13.