Fix fencepost error in leaderboard code.
Merge pull request #806 from kmaglione/leaderboard-fencepost

Fix fencepost error in leaderboard code.
Fix level headings being printed multiple times in reviewer leaderboard.
Merge pull request #807 from kmaglione/moar-leaderboard-fixes

Fix level headings being printed multiple times in reviewer leaderboard.
fix rereviewqueuetheme cascade delete (bug 882010)
Merge pull request #803 from ngokevin/themethumbnails

install btn, artist tools, review status to theme thumbnails (bug 565179)
fix up theme thumbnails patch