Merge pull request #3440 from edx/ammar/config-youtube-stub-for-bok-choy

cms/djangoapps/contentstore/features/video.py

cms/envs/bok_choy.py

common/djangoapps/terrain/start_stubs.py

common/djangoapps/terrain/stubs/tests/test_youtube_stub.py

common/djangoapps/terrain/stubs/youtube.py

common/test/acceptance/pages/lms/video.py

lms/djangoapps/courseware/features/video.py

lms/envs/acceptance.py

lms/envs/bok_choy.py

rakelib/bok_choy.rake