Allowing manual marking of devices that are for demo/testing purposes only, and display in the central server control panel.
Merge branch 'release-0.10' of github.com:learningequality/ka-lite into mark_demo_devices

Conflicts:
	kalite/control_panel/views.py
	kalite/templates/control_panel/zone_management.html
Merge branch 'master' of github.com:learningequality/ka-lite into mark_demo_devices
removing merge conflict marker
Merge branch 'release-0.10' of github.com:learningequality/ka-lite into mark_demo_devices
Merge pull request #672 from bcipolli/mark_demo_devices

Allowing manual marking of devices that are for demo/testing purposes only