[NEXUS-6072] Refactor internal capability reference statuses & error handling

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
[NEXUS-6070] Transition capability to removed regardless if onRemove() fails

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
[NEXUS-6072] Replace AbstractLoggingComponent -> ComponentSupport

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
[NEXUS-6072] Log stack trace only on debug level

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Merge pull request #215 from sonatype/NEXUS-6072-failure-during-capab-load

REVIEW: [NEXUS-6072] Refactor internal capability reference statuses & error handling