JCR-3587: RepositoryImpl should expose the collection of PersistenceManager instances in use.

Porting down r1478757,r1478719:
Make the RepositoryConfig and WorkspaceInfo instances available through RepositoryContext, allow the persistence manager to be retrieved.



git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/branches/2.6@1478861 13f79535-47bb-0310-9956-ffa450edef68