Adding templatetag to djblets.siteconfig

Review Request #678 — Created Dec. 18, 2008 and discarded — Latest diff uploaded

Review Board SVN (deprecated)
Added a templatetag which allows for nabbing siteconfig values in context. More or less a copy of similar efforts done in Django 1.0 for rendering forms inline without need for passing variables into templates.
No new code, really. Straight copy from django.forms. Used routinely.