Added DNS name of the VM being deleted. This is to handle the case where multiple deployments exist with the same VM names (for e.g. multiple VMs called 'swarm-master' but under different cloud services).
Added DNS name of the VM being deleted. This is to handle the case where multiple deployments exist with the same VM names (for e.g. multiple VMs called 'swarm-master' but under different cloud services).

rgardler/azure-swarm,avranju/azure-swarm