* Fix issue1811: take limit_choices_to into account with FK
* Issue 1811: Add tests to illustrate issue
* Filter queryset only if limit_choices_to exists
* Move test_relations_with_limited_querysets file within test_relations_pk
* move limit_choices_to logic from relations.py to utils/field_mapping.py
* move limit_choices_to above other check to avoid conflicts
* Identify code that needs to be pulled out of/removed from compat.py
* Extract modern code from get_names_and_managers in compat.py and remove compat code
* Extract modern code from is_authenticated() in compat.py and remove.
* Extract modern code from is_anonymous() in compat.py and remove
* Extract modern code from get_related_model() from compat.py and remove
* Extract modern code from value_from_object() in compat.py and remove
* Update postgres compat
JSONField now always available.
* Remove DecimalValidator compat
* Remove get_remote_field compat
* Remove template_render compat
Plus isort.
* Remove set_many compat
* Remove include compat
- In both ManyRelatedField, provide an empty return when trying to
access a relation field if the instance in question has no PK (so
likely hasn't been inserted yet)
- Add relevant tests
- Without these changes, exceptions would be raised when trying to
serialize the uncreated models as it is impossible to query
relations without a PK
- Add test to ensure RelatedField does not regress as currently
supports being serialized with and unsaved model
* Get rid of runtests.py
* Moved test code from rest_framework/tests and rest_framework/runtests to tests
* Invoke py.test from setup.py
* Invoke py.test from Travis
* Invoke py.test from tox
* Changed setUpClass to be just plain setUp in test_permissions.py
* Updated contribution guideline to show how to invoke py.test
