Redid set_video_id as data migration, using orm references, not imports
Add CronCommand - a command that can only be run from the command-line.  Why you'd want this: to interact with chronograph easily, but to force the command to be run within the server process.
Get youtube-dl working with callbacks.
Fix for #1455: don't retry non-connection errors
Force runserver and runcherrypyserver through kaserve, EXCEPT on a 'stop'
Final change for #1375 - move all data out of web-accessible directory.
Moved fixed migration code to a new 0029, and made 0028 into a dummy.

(as the old 0028 had already been shipped)
Adding acceptable formats and tooptip
Add translation tag
Merge pull request #1651 from bcipolli/1375

Final change for #1375 - move all data out of web-accessible directory.
Merge pull request #1649 from bcipolli/force_kaserve

Force runserver and runcherrypyserver through kaserve, EXCEPT on a 'stop'
Merge pull request #1665 from wangguan59/math_format

Adding acceptable formats and tooptip
added another hint png example
Fix for #1662: re-apply KA-LITE-MOD to khan-exercises
add missing qtip2 css, cleanup
Merge pull request #1645 from jamalex/set_video_id_migration

Redid set_video_id as data migration, using orm references, not imports
Adding comment to i18n/__init__.py, to try and warn against breaking main migrations.
Merge pull request #1666 from bcipolli/1662

Fix for #1662: re-apply KA-LITE-MOD to khan-exercises
Merge pull request #1667 from mauk81/develop

add missing qtip2 css
Change default debug central server host