Merge pull request #10873 from edx/kill-callstackmanager

cms/envs/test.py

lms/djangoapps/courseware/migrations/0001_initial.py

lms/djangoapps/courseware/model_data.py

lms/djangoapps/courseware/models.py

lms/djangoapps/courseware/user_state_client.py

lms/envs/test.py

openedx/core/djangoapps/call_stack_manager/__init__.py

openedx/core/djangoapps/call_stack_manager/core.py

openedx/core/djangoapps/call_stack_manager/models.py

openedx/core/djangoapps/call_stack_manager/tests.py