added missing swappable migration option to prevent the creation of the swappable model if alternative model is provided.
added missing swappable migration option to prevent the creation of the swappable model if alternative model is provided.

DeskConnect/django-oauth-toolkit,JensTimmerman/django-oauth-toolkit,StepicOrg/django-oauth-toolkit,JensTimmerman/django-oauth-toolkit,DeskConnect/django-oauth-toolkit,bleib1dj/django-oauth-toolkit,bleib1dj/django-oauth-toolkit,StepicOrg/django-oauth-toolkit