Should validate provided master node

[godber]

The cluster master node is provided as an argument to the script. The script should at the very least check to see if a ES cluster is on the provided host and port. It would be best to verify that all of the provided nodes and master are members of the same cluster too.

[godber]

This ticket was so great I wrote it twice! dupe #5

[erik-stephens]

Instead of having using provide as an arg, how about looking up the currently elected master automatically? Removes a manual step and some potential for human error.

[godber]

I think I get what you're saying. You're saying that we shouldn't bother providing a master at all, it should be queried from the hosts in the list, right? That's a good idea. Given that, my concern still exists ... I am afraid of a case where people create a list that has nodes from two different clusters. We should ensure that all the nodes in the list are in the same cluster. That's the main point of this ticket.