Add comments to Role and User models.
Stop validating presence of name.
Add comments for new User attributes.
Require username and that it be unique.
Merge branch 'master' into add-s3-to-user

* master:
  Require username and that it be unique.
  Add comments for new User attributes.
  Stop validating presence of name.
  Add comments to Role and User models.

Conflicts:
	app/models/user.rb
Add ability to update S3 config.