Adding first management command, to check data expectations / integrity
Merge branch 'develop' into dashboard_stats_1

Conflicts:
	kalite/settings.py
Merge branch 'release-0.11' of github.com:learningequality/ka-lite into dashboard_stats_1

Conflicts:
	kalite/settings.py
Cleaning up settings, to only load apps as appropriate.
refactoring shared/serializers to django_utils/serializers; moving default version passing to the securesync engine wrapper
Remove unused serverstop script, move generic middleware to django_utils
Fix for #1497 - What is the purpose of the "--" language?
First pass to add footer; addresses #1522 and #1523
Tiny tweaks to logo styling
Backing out: don't select any language pack for download by default in the update languages page
Fix for #1497 - What is the purpose of the "--" language?

Remove the "--" option
bundle youtube_dl and use it as a library
Add back callback_url parameter, to complete distributed server registration via a direct callback url.
removing khan-exercises
Squashed 'kalite/static/js/khan-exercises/' content from commit e550618

git-subtree-dir: kalite/static/js/khan-exercises
git-subtree-split: e550618b86d22cf5eb3738e46b6be358a0e7f014
Merge commit 'b927bd58ae409e78358e4b56fdbd4986a3e78b68' as 'kalite/static/js/khan-exercises'
remove inline styles and disabled classes
Merge branch '1522' of github.com:bcipolli/ka-lite into 1522
Merge pull request #1583 from bcipolli/1522

Changing footer and language drop-down styling
Fix for #1457 - don't show "current" progress bar when using youtube-dl in video download