[1093822] RFE: Allow automatic uninventory of dead / missing / removed resources
Initial commit for consideration.  Plugin components can now report DEAD
availability for resources that seem physically removed from the system. DEAD
resources can then be configured for automatic uninventory via a new Admin
GUI view.
[1093822] RFE: Allow automatic uninventory of dead / missing / removed resources
Changing "DEAD" to "MISSING" in response to terminology feedback.
[1093822] RFE: Allow automatic uninventory of dead / missing / removed resources
Fix a few merge issues.