Tighten up the logic for looking up drafts

Review Request #605 — Created Oct. 21, 2008 and submitted — Latest diff uploaded

Review Board SVN (deprecated)
Our support for looking up drafts was inconsistent. Sometimes we'd do the right thing and make sure we only looked it up based on the user, and sometimes we just simply checked for a draft. We're now looking them up right in all places.
Passed unit tests, and the draft banner seemed right on each page.