Add owner's avatar URL to the event payload.
Merge branch 'master' into mm-add-avatar-url-to-event-payload
Add github_language to the API payload.
An build data.
Merge pull request #250 from travis-ci/mm-add-avatar-url-to-event-payload

Add avatar url to event payload
Add avatar_url to User.
Send pull request information with build created and started events
Raise if github_id does not match when updating user
Use non unique index on repsitories(github_id) for now

We can't have unique index on github_id on production, because we have
some duplicates in the DB. An unique index will be added when we deal
with it.