Fix file attachment URLs in change descriptions on local sites.
Review Request #6262 — Created Aug. 24, 2014 and submitted
We didn't have the LocalSite name in the template, breaking links. This
fixes the templates to contain this information.
Tested on RBCommons and saw that the link worked and the page didn't crash.
Tool: Pyflakes Processed Files: reviewboard/reviews/builtin_fields.py Tool: PEP8 Style Checker Processed Files: reviewboard/reviews/builtin_fields.py