Bug 1079303 - Excessive database size when using bundles causing UI to fail

Do not load histories when showing the deployments view.
Fetch histories aync when unfolding a resource deployment.

Added index on resource deployment id in audit table
->Fast fetch histories aync when unfolding a resource deployment in the UI
Dropped foreign key on resource deployment id in audit table
->This is to prepare the async deletion of orphan audit messages when deleting a bundle deployment (or a bundle version, or even the bundle itself)
->Documented in db-upgrade.xml and content-schema.xml why we are breaking the rule (dropping an FK)

Added GUI messages when deleting version/destination/deployment/bundle so that the user gets correctly informed of what is going on

No longer cascade remove audit message when deleting resource deployments
Purge orphaned audit messages in DataPurgeJob
No direct purge of audit messages during async resource deletion job

Also, increased the default batch size property, as testing showed 1.5x higher performance (tested on 1 million and on 5 million rows).
A community user with a large RHQ deployment reported better results with higher batch size as well.

getBundleResourceDeploymentHistories returns a copy of resourceDeployment.getBundleResourceDeploymentHistories():
1. It's safer (no direct entity collection manipulation)
2. GWT Serializer does not accept Hibernate's persistent bags