Extend remote get test scenarios to test the joiner state

I got a failure in testScenario6, and I think it's because the originator retried the get command on the joiner, but the joiner hadn't installed the currentTopology+2 topology, and ClusteredGetCommand.perform() returned an unsure response. I guess I we'll have to rethink the unsure response stuff after all...

Here's the log: https://www.dropbox.com/s/dka0vdwm719klkm/RemoteGetDusingStateTransfer.tgz