make beta dash compute module_state_key like legacy dash (LMS-2491)
add failing tests
Refactor video caption module.
Test TemplateLookup dirs are not cleared during lms startup.

LMS-2498
make sure new lms/tests.py file is run
Merge pull request #3153 from edx/anton/caption_refactor

Refactor video caption module.
Merge pull request #3205 from edx/usman/lms2498-mako-template-tests

Test that TemplateLookup dirs are not cleared during lms startup
Merge pull request #3187 from edx/adam/fix-alter-xblock-student-state

Adam/fix alter xblock student state
BLD-970: Fix flaky test.