Fixed #20730 -- Fixed "Programmatically creating permissions" error.

example, you can create the ``can_publish`` permission for a ``BlogPost`` model

in ``myapp``::

    from myapp.models import BlogPost

    from django.contrib.auth.models import Group, Permission

    from django.contrib.contenttypes.models import ContentType

    content_type = ContentType.objects.get(app_label='myapp', model='BlogPost')

    content_type = ContentType.objects.get_for_model(BlogPost)

    permission = Permission.objects.create(codename='can_publish',

                                           name='Can Publish Posts',

                                           content_type=content_type)