Bug 1033130 - [AS7] Exception during discovery of Query Cache resources of RHQ Server resource

Instead of importing tons of Query Cache resources, AS7 plugin will mimic Hibernate Plugin's behavior and expose a "viewQueries" operation to gather the Query Cache nodes statistics.

Added HibernatePersistenceUnitComponent to implement "viewQueries" operation. The operation processes Query Cache nodes in batches to avoid sending too many queries to the management interface
Deleted the never used QueryCacheDiscovery class (updated API check file accordingly)
Removed the commented-out Query Cache service in AS7 plugin descriptor and added the "viewQueries" operation on the Hibernate Persistence Unit service
Added itest for the "viewQueries" operation