Exposed the existing "disableAutoSync" property of ClusterNode to external configuration.

[tduffey]

With this change you can now define your cluster config with an additional param to disable auto sync:

  <Cluster syncDelay="2000" disableAutoSync="true">
    <Journal class="org.apache.jackrabbit.core.journal.DatabaseJournal">
      ...
    </Journal>
  </Cluster>

With this we now have the ability to start a cluster node, allow it to synchronize to the latest journal revision at startup and then stop without worrying about any additional changes being sync'd via the normal journal sync process. The use case is to define a node like this to periodically launch, get the latest updates, stop and then save a backup.

I would be happy to provide a different unit test if you can suggest what sort of test you'd like to see since this is a very minimal change.