Add prefetch_related method to FakeQuerySet
Add prefetch_related method to FakeQuerySet

We can emulate the effect of prefetch_related with the recent (Django
1.10) django.db.models.prefetch_related_objects - this should mean
one less queryset method that causes an error when applied to a
FakeQuerySet.

torchbox/django-modelcluster,wagtail/django-modelcluster