Update Video component docs per BLD-837
fixes css to render properly poll module (BLD-839)
BLD-837: Fix download transcript behavior.
LMS: adding language selector to user dashboard (WIP)
wiring for language selector
Added dark lang database fixture to bok choy tests
Acceptance test for language selector

Tests language selection feature for student dashboard
LMS: simplifying language settings modal controls UI
Moved UserPreferences to common
Replace rake functions with python paver functions
Deprecated rake functions issue a warning and then call paver
replacements

Bring Paver commands up to date with master for servers, assets, and docs.
Revert deprecation of quality, tests, and i18n for a future pull request.
Deprecate workspace migration
First rough cut of a container page.
Couple more changes
updated container header styling and exposed sidebar back to its location. includes some javascript to render tooltips on overflowed text headers
Merge pull request #2520 from edx/will/paver-rebase-part-1

Paver (Part 1)
styling for recursive xblock rendering structure to be used in the container page, pulling from general xblock styles in a separate file.
Add "Additional Transcripts" section to Video topic
Merge pull request #2507 from edx/marco/studio/container-view

styling for a generic container view in Studio built on top of base styles for xblocks rendered in Studio. Also includes UX reference template area for unit and container pages.
Fixed broken image in LTI Component topic
Clarify one advanced setting for video components
Merge pull request #2604 from edx/sylvia/documentation/BLD-841

Fixed broken image in LTI Component topic