Restore django.pot
Looks like we need to explicitly specify we want to keep the pot file now.
Not sure why we need it, as it is supposed to be temporary according to https://docs.djangoproject.com/en/dev/ref/django-admin/#django-admin-option---keep-pot
However, tx set doesn't work without it currently, and Transifex proposed it for download during translation, so it probably doesn't hurt to keep it.