stop update_assets commands from being called extra times
Add Studio handling for changes to group configurations

STUD-1658
Introduce constants for studio_view, student_view, and author_view.
Complete Studio support for handling group configuration changes

STUD-1658
Disable periodically failing Bok Choy test
Merge pull request #3999 from edx/christina/updating-split-test

Ability to change the associated group configuration for a split test