v2.5.0

2.5.0 constitutes a major, backwards incompatible release that factors custom Django models and the import_data management command out of django-councilmatic. Instead, django-councilmatic>=2.5.0 extends the Django implementation of the Open Civic Data standard, python-opencivicdata, and updates application code throughout to accomodate the model changes. Approaches for further extension of the base models are outlined in the README.