Password injection requires either hypervisor-support or an agent
running in the guest that will talk to the metadata service. It can be
disabled for a deployment using the '[api] enable_instance_password'
nova config option. Indicate this, albeit briefly.
Change-Id: Ief94ea07fc7ab6a487af972e8759ca6704d8f085
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>