Bug 1053483 - RHQ Admin UI references 'Cassandra' rather than storage node

I am opening up this as a pull request to get answer for a simple question:

"How to rename a resource type?"

I can see 2 ways of doing this.

1. rename resource type. This would cause the original "Cassandra Server JVM" resources to disappear and new "JVM" would be discovered.
 - drawback - metric history is lost

2. keep resource type name and update discovery/upgrade code - this approach keeps all metrics and can rename existing resources and give proper name ("JVM") to new resources. 
 - drawback - resource type is still called "Cassandra JVM Server"

3. may be to add support for resource type name change to plugin descriptor (ie. via new attribute oldName), then we can pair old and new resource type and we don't remove the old type and insert new one.

I've chosen 2. because I think it is important to keep metrics especially for storage nodes.