The API docs were broken by the Django 1.11 upgrade. This change includes an upgrade to the most recent version of django-rest-swagger that supports DRF 3.4. Newer versions of django-rest-swagger require DRF 3.5.

This change is complicated by a decision made by the maintainers of the django-filter package to avoid subclassing DRF's DjangoFilterBackend. For more on that decision, see https://github.com/carltongibson/django-filter/pull/576. The SchemaGenerator from DRF 3.4.7 expects instances of DjangoFilterBackend to have a get_fields() method. The DjangoFilterBackend from django-filter 1.0.4 doesn't have this method, instead replacing it with the get_schema_fields() used by the SchemaGenerator in DRF 3.5. To work around this, I've replaced our one use django-filter's DjangoFilterBackend with DRF's DjangoFilterBackend. Note that DRF 3.5 removes its implementation of DjangoFilterBackend in favor of django-filter's, so we will have to change how we import DjangoFilterBackend when we upgrade to 3.5.

LEARNER-1590