Fixed #21829 -- Added default AppConfigs.
Fixed #21829 -- Added default AppConfigs.

Thanks Russell for the report, Marc for the initial patch, Carl for the
final review, and everyone who contributed to the design discussion.

barseghyanartur/django-formtools,barseghyanartur/django-formtools,lastfm/django-formtools,thenewguy/django-formtools,lastfm/django-formtools,thenewguy/django-formtools,gchp/django-formtools,gchp/django-formtools