Merge pull request #9929 from edx/bbeggs/merge-DRF-3.1

cms/envs/common.py

common/djangoapps/cors_csrf/tests/test_authentication.py

common/djangoapps/enrollment/data.py

common/djangoapps/enrollment/serializers.py

common/djangoapps/enrollment/tests/test_views.py

common/djangoapps/request_cache/__init__.py

common/djangoapps/request_cache/tests.py

common/test/acceptance/tests/lms/test_teams.py

lms/djangoapps/commerce/api/v1/serializers.py

lms/djangoapps/commerce/api/v1/views.py

lms/djangoapps/course_structure_api/v0/serializers.py

lms/djangoapps/course_structure_api/v0/tests.py

lms/djangoapps/course_structure_api/v0/views.py

lms/djangoapps/courseware/grades.py

lms/djangoapps/discussion_api/api.py

lms/djangoapps/discussion_api/pagination.py

lms/djangoapps/discussion_api/serializers.py

lms/djangoapps/discussion_api/tests/test_api.py

lms/djangoapps/discussion_api/tests/test_serializers.py

lms/djangoapps/discussion_api/tests/test_views.py