Parallel cluster connectivity status check

I've added a command line option to perform a connectivity test of all nodes. It's useful if you want all your nodes to be up before starting and aren't sure if they are. I thought this would be useful as I've had a desire for it sometimes, especially when working with Amazon EC2 nodes.

moscrack --status

It connects to each node using it's normal connectivity method (the same way Moscrack does status checks). All nodes are connected in parallel, so it's pretty fast even with a large cluster.