Set a fixed host for nova in boot-stack.

This makes the registration scripts be able to depend on the hostname,
irrespective of the static hostname in the base image used for seed
nodes.

Change-Id: I6bc1c2560d2d548ab99cb6f4129c70e572a918dc
Another os-apply-config rename step.

Change-Id: I37d6e0fc5adbc62d9742a4c143e26af3793fd32a