QPID-5409: Refactor BDB  HA MBean to delegate the operations to the underlying node configured object.
Unregister BDB HA MBean on virtual host deletion or replication node removal

git-svn-id: https://svn.apache.org/repos/asf/qpid/branches/java-broker-bdb-ha@1565308 13f79535-47bb-0310-9956-ffa450edef68