Modernize course_groups

openedx/core/djangoapps/course_groups/api.py

openedx/core/djangoapps/course_groups/cohorts.py

.../core/djangoapps/course_groups/migrations/0001_initial.py

...ups/migrations/0002_change_inline_default_cohort_value.py

...oapps/course_groups/migrations/0003_auto_20170609_1455.py

openedx/core/djangoapps/course_groups/models.py

openedx/core/djangoapps/course_groups/partition_scheme.py

openedx/core/djangoapps/course_groups/serializers.py

openedx/core/djangoapps/course_groups/signals/signals.py

openedx/core/djangoapps/course_groups/tests/helpers.py

...edx/core/djangoapps/course_groups/tests/test_api_views.py

openedx/core/djangoapps/course_groups/tests/test_cohorts.py

...e/djangoapps/course_groups/tests/test_partition_scheme.py

openedx/core/djangoapps/course_groups/tests/test_views.py

openedx/core/djangoapps/course_groups/urls.py

openedx/core/djangoapps/course_groups/views.py