[replication] RSM won't cleanup after locking if 0 peers

Small bug in ReplicationSourceManager, it won't cleanup after locking another's RS znode if it didn't contain any queue at all. It happens in transferQueues():

LOG.info("Moving " + rsZnode + "'s hlogs to my queue");
    SortedMap<String, SortedSet<String>> newQueues =
        this.zkHelper.copyQueuesFromRS(rsZnode);
    if (newQueues == null || newQueues.size() == 0) {
      return;
    }
    this.zkHelper.deleteRsQueues(rsZnode);

That last line should be before the if, so that it deletes the lock znode and the RS znode. Currently a lot of cruft piles up in ZK after a few restarts with replication enabled and no queues, or in slave RSs.