conslidated migrations for nidm.
unique_together is not usable with Django-polymorphic.  it doesn't traverse foreign keys.
TODO: implement a custom validate_unique:
https://docs.djangoproject.com/en/dev/ref/models/instances/#django.db.models.Model.validate_unique
nidm cleanup and copy after upload
fix for polymorphism problem with unique_together.  difficult issue.
Added API listings for NIDM