Remove cluster member

Remove node from a cluster. See https://trello.com/c/xarZEs6g/846-ha-support-removing-nodes-from-clusters

Originally https://github.com/crowbar/barclamp-pacemaker/pull/100, but rebased and requested against master 

https://github.com/crowbar/barclamp-crowbar/pull/1011 is needed so the remove role get correctly deleted after it is used once.
I'd hope "some flag that says node is still a cluster member and is not intended to be removed" is exactly the situation when node has a pacemaker-cluster-member_remove role assigned.

I think at the point when pacemaker-cluster-member_remove is added, pacemaker-cluster-member was already removed (but I did not check the code)