reconfigure rest-framework;
enable admin to save lessons
Merge branch 'master' into activity-admin

Conflicts:
	lesson/serializers.py
add save button for lessons in course admin page
Merge remote-tracking branch 'origin/master' into activity-admin
allow edit a simple question in course admin page
Merge remote-tracking branch 'origin/master' into activity-admin
found unsolved bug in admin page
reference selectedUnit by unit index instead reference
Merge remote-tracking branch 'origin/master' into activity-admin
remove unused javascript functions
remove unused view test