Add Option for Disable Cache/Instance Management

Add support for disable cache or instance management in TObjectManager.

Or an alternative: refactor TOBjectManager in two components: TObjectPersistence and TObjectManager, where TObjectPersistence deals just with the persistence task (reading and writting entities from database through criteria API) and TObjectManager with management of instances of the Entities. As TOBjectPersistence components does not cache instances, associated entities should not share instances among the entities.