Fix bug 977850: Add support for creating text banners.
Install pytz.
Enable timezone support and set default timezone to UTC.

Also fixes instances that were using non-aware datetimes.
Add helper for retrieving gravatars.
Bug 976809: Add management command for updating leaderboard.

- Also update collect_ga_data to batch bulk data insertion in case MySQL
  decides it's not waiting for a crapton of data.
- Add a script to bin for running the nightly update tasks.
Partial integration of leaderboard template.