Get usernames by backend method
Get usernames by backend method

Replaces multiple attempts at generating a username with reference to a
default base method. Updates the base method using powlo's previous
update: 57c7b5bd10524b61a6f00deafa5be613fe6595ff@fd712a509f4ae135f18403b6e476529795d17314

arteria/django-ar-organizations,bennylope/django-organizations,aptivate/django-organizations,DESHRAJ/django-organizations,aptivate/django-organizations,st8st8/django-organizations,aptivate/django-organizations,bennylope/django-organizations,GauthamGoli/django-organizations,st8st8/django-organizations,DESHRAJ/django-organizations,GauthamGoli/django-organizations,arteria/django-ar-organizations