Use libravatar instead of PIL
Comment out the ImageField in the legacy SpeakerRegistration model
Revert pillow requirement removal. We expect to still have ImageFields
Explain where avatars come from
We now require all users to have e-mail addresses

Or their profile pages will fail to render
Merge pull request #1 from CTPUG/libravatar

Use libravatar for User mugshots
I knew there was a DRY way to do it...
Merge remove_speaker_registration and fix merge conflict
pyflakes cleanups