This patch adds installation of virtualbmc and plugging VMs into it as
part of 'bifrost-create-vm-nodes' role.
The baremetal data file is now populated with nodes using
"agent_ipmitool" driver.
All things defaulting to some *_ssh drivers are replaced with
corresponding *_ipmitool drivers.
Most libvirt and VM related tasks (including some SSH key management)
and vars are moved from 'bifrost-ironic-install' role to
'bifrost-create-vm-nodes' role, as ironic istelf now should barely care
about libvirt as no *_ssh drivers are used.
Change-Id: If42082e5b1fe8b83a364e27efc549bb74a19ab2f
Closes-Bug: #1659876
12376b958e