devstack: use password with version discovery
devstack: use password with version discovery

Devstack will move to keystone v3, so support it here.

Change-Id: I2a6eb7ec63ab6d2d7ac5c8e162ef96197137a966
Closes-bug: #1539728

idegtiarov/ceilometer,ityaptin/ceilometer,ityaptin/ceilometer,idegtiarov/ceilometer,openstack/ceilometer,openstack/ceilometer