Merge pull request #2280 from learningequality/nalanda-rct2

Nalanda rct2 to nalanda
Merge pull request #2304 from learningequality/nalanda-prerelease

Nalanda prerelease into release
Merge pull request #2319 from learningequality/nalanda-prerelease

Releasing recent Nalanda fixes
Merge branch 'nalanda-rct2' into nalanda-prerelease
Merge branch 'nalanda-prerelease' into nalanda
Merge pull request #2341 from learningequality/nalanda-rct2

Release Nalanda RCT2 updates
Merge pull request #2342 from learningequality/nalanda-prerelease

Nalanda prerelease
Merge pull request #2412 from learningequality/nalanda-rct2

Nalanda rct2 to nalanda rct3
Merge pull request #2475 from anuragkanungo/nalanda-rct3

 Fix for First Login After SignUp -- Asks for Signup again
Hide playlists assigned in other units.
Adds unit for 'gift cards' for quiz points.
Linting.
Prevents teachers from altering units for other facilities.
Removes unit links on current unit page for all users.
Hides previous unit button for teachers.
Bumps query tests to account for additional database read for unit settings.
Fixes Unit related tests due to teacher changes.
Merge pull request #2498 from rtibbles/rct3_fixes

Client side Unit for Gift Cards and Restrict Displayed Playlists to Current Unit
Added playlist-related models to admin.py to show in admin.
Merge branch 'nalanda-rct3' of github.com:learningequality/ka-lite into nalanda-rct3
create add_new_playlists management command
append the new playlists to the old playlists file