Customizablility of modal boxes.

Review Request #1293 — Created Dec. 4, 2009 and submitted — Latest diff uploaded




This is a small change to djblets that allows us to easily change the class of a modal box.  This allows reuse of existing tech for reviewboard rather than integrating thickbox into our help system.  See screenshot below for example (implementation of exact dialog will be added to request 1281 )
Local against mainline djblets + change and mainline reviewboard.