Merge branch 'release-0.10' of github.com:learningequality/ka-lite into avoid_command_infinite_loops

Conflicts:
	kalite/main/management/commands/subtitledownload.py
	kalite/main/management/commands/videodownload.py
	kalite/templates/video_download.html
calculate the proper ordering of syncing models, verify that there are no loops.
Merge branch 'release-0.10' of github.com:learningequality/ka-lite into force_sync
expose a simple endpoint for launching syncmodels, expose a button for launcing that API endpoint
moving button to easy_admin page, fixing debug-only class
slightly better UI with no extra div
Merge branch 'release-0.10' of github.com:learningequality/ka-lite into force_sync
Merge branch 'user_list_admin_indicator' of github.com:rtibbles/ka-lite into release-0.10.0
Performance: intercept api/v1 urls in nginx, and return {}
Merge pull request #559 from gimick/nginx_apiv1_speedup

Performance: intercept api/v1 urls in nginx, and return {}
Merge branch 'release-0.10.0' into avoid_command_infinite_loops
renaming misnamed 'total_logins' to 'count'
Merge pull request #565 from bcipolli/rename_total_logins

HOTFIX: renaming misnamed 'total_logins' to 'count'
Merge branch 'rename_total_logins' of github.com:bcipolli/ka-lite into release-0.10
Make video downloading more robust; e.g., auto-restart after dropout.
Removed "cs" topic from the topic tree, as it is broken/mostly empty.
cannot take max on None; add max_none function
another bugfix redo
Merge pull request #570 from bcipolli/max_none

HOTFIX: Max on list containing None fails.
added more useful message, only show button if registered.