Highlight device when unregistered on zone management.
Style buttons ready for bootstrap integration.
Merge branch 'develop' of github.com:learningequality/ka-lite into highlight_device
Implemented unregistered device highlighting via template tags.
Reverted register now to link.
Small style tweaks to register now link.
Merge pull request #1818 from rtibbles/highlight_device

Highlight device when unregistered on zone management.