Add "stage_status", to track (and report) errors and cancellations.
Use stage_status for better video updates (better error reporting)
fixing small bug in update
Merge branch 'release-0.11.1' of github.com:learningequality/ka-lite into smoother_updates
Merge pull request #1176 from bcipolli/smoother_updates

Smoother updates (particularly video updates)