In OSP-17 and newer, there is no Nova running as undercloud
service and instead of Nova client, Metalsmith client has to be
used to e.g. get overcloud nodes and its IP addresses.
This patch replaces Nova client with Metalsmith client to list
overcloud servers and it IP addresses
Change-Id: I0a7859ebc4e1c6d3660040100e1bf55a7218e4f2