Add credentials to wait_for_keystone
Add credentials to wait_for_keystone

With this patch, the caller of wait_for_keystone does not have to ensure
that the credentials for keystone are in the environment --
wait_for_keystone sources them and drops them again when it is done.

Change-Id: I37f47fd3d804681d95416ded90db273aa10f2aaf

openstack/training-labs,openstack/training-labs,openstack/training-labs