Work around Django <= 1.5 generic relations problem.

The ORM changed significantly between Django 1.5 and 1.6, changing
the way filters and therefore get_or_create work over generic relations.

http://stackoverflow.com/questions/22200791/django-generic-foreign-key-filtering-difference-between-v1-5-v1-6

This nasty hackery gets the Popolo importer working with Django 1.4.
I'm looking forward to removing it again when support for 1.4 is
dropped.