labs: set authentication host (OPENSTACK_HOST)
labs: set authentication host (OPENSTACK_HOST)

Set OPENSTACK_HOST (default: 127.0.0.1) to controller-mgmt.

Change-Id: I54e4aa5786426d30074a51100162a53f9d1768f7

harrisonfeng/training-guides,Nabs007/training-guides,Nabs007/training-guides,harrisonfeng/training-guides,openstack/training-guides,openstack/training-guides,Nabs007/training-guides,harrisonfeng/training-guides