Switch off of Elasticsearch as main storage.

this deviates from the [Model.clean](https://docs.djangoproject.com/en/1.7/ref/models/instances/#django.db.models.Model.clean) definition (which takes no arguments and operates on instance data in-place) - I think it would be best to override the classmethod `Model.create` to populate the model from dict values, and then use `Model.clean` only if needed to provide custom validation that the default implementation doesn't provide.