[1093822] RFE: Allow automatic uninventory of dead / missing / removed resources
Changing "DEAD" to "MISSING" in response to terminology feedback.

(cherry picked from commit 78df7de3618ac64f5e7595d54fa1ad30121e4f36)

Conflicts:
	modules/enterprise/server/jar/src/main/java/org/rhq/enterprise/server/resource/ResourceTypeManagerBean.java
[BZ 1069545] Align subsystems subcategories with EAP admin console.