Display multiple revs in Web UI for multiple codebase setups

Currently, the web UI only shows "multiple rev" when viewing Builder pages. This is entirely
unhelpful. This patch changes it so it will show the revisions (including codebase) wherever
possible.
 MultiRev: fix minor error in Jinja templates
MultiRev: address review comments

Prefer 'got_revision' to 'revision' field
Merge branch 'MultiRevOnWeb' of git://github.com/jaredgrubb/buildbot