stop leaking service as a global var
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
(cherry picked from commit f0bd8dbe37bd855669ad4cddff0a49bccfd9b64e)

williamthegrey/devstack