stop leaking service as a global var

the tls code was leaking out $service as a global variable, which
was causing all manner of confusing errors in grenade trying to
use that variable name. All lower case vars should be localize.

Change-Id: I74fa597f20ee7c714cab83490b42d874ea93db02
add is_keystone_enabled

This is missing, and makes logic much harder for the grenade use
case.

Change-Id: Ib6670096d190e69273256b87e6a67e2b46945a0d
Merge branch 'master' of github.com:openstack-dev/devstack