Fix Transifex configuration so we can merge translations
Add Chinese (Hong Kong) language
Fix failing test and update docstrings for video player

Fixes BLD-1115
Merge pull request #4055 from edx/sarina/fix-underscore-resource

Sarina/fix underscore resource
Merge pull request #4074 from edx/alex/fix_video_saved_editor

Fix failing test and update documentation of video player
Ignore *.css.map files
Merge pull request #4076 from edx/sarina/ignore-maps

Ignore *.css.map files
Studio: adding language selector to user dashboard
Studio: use UserPreferences & lang_pref in lang display/selection
Add click handlers
Hook up lang middleware & django i18n support
Wire up Cancel button
Hide language menu in Studio when no released langs
i18n buttons