store status of why a background charm was disabled

[anotherjesse]

when a charm is disabled we mark it as disabled. We should also store the reason it was disabled.

[linear]

COM-320 store status of why a background charm was disabled

[anotherjesse]

might be limited by #924 - but perhaps not

[anotherjesse]

Lots of "timed out after 10 seconds"...

Which sometimes instantly pass when re-enabled ... sometimes not

[anotherjesse]

Fixed with #954