Fixes #3409
Bok-Choy video tests batch2
Reword docstrings for bok-choy video tests
Merge pull request #3425 from edx/pk-set-can-be-none

pk_set can be None
Merge pull request #3341 from edx/ammar/bok-choy-video-tests-batch2

Convert video tests from lettuce to bok-choy - batch 2
Release notes draft 4-23-14
Merge pull request #3430 from edx/markhoeber/documentation/doc-273

Release notes draft 4-23-14
properly remove users from instructor/staff groups on a course delete
STUD-1555
Merge pull request #3304 from edx/zub/story/deletecoursegroups

properly remove users from instructor/staff groups on a course delete
Set initial video quality to large instead of default to avoid automatic switch to HD when iframe resizes. [BLD 981]