Prevent and enable fixing of multiple primary email addresses.
Fixes https://github.com/pennersr/django-allauth/issues/216
Merge pull request #217 from sssbox/fixes_optional_email

Fixes https://github.com/pennersr/django-allauth/issues/216
Merge pull request #211 from sssbox/prevent_multiple_primary_email

Prevent and enable fixing of multiple primary email addresses.
Rename command to unset multiple primary emails
Merge branch 'master' of git://github.com/pennersr/django-allauth into anonymizers
Fix unique anonymizer.