Aligns Keystone auth_uri with other OpenStack Services

Previously, auth_uri had a default address of 127.0.0.1 as did
the keystone_host parameter.  This caused problems for users that
use a different IP address for Keystone.  This can cause issues
where the keystone host is an actual address and the auth_uri still
uses 127.0.0.1.  Additionally, this patch will allow the auth_uri
behavior to be consistent with the other OpenStack modules.

Conflicts:

        manifests/init.pp
        spec/classes/heat_init_spec.rb

Change-Id: I81fc650606c419d25a2e13dc2093c8e4538fb997
(cherry picked from commit 4a5a5849a5088290bf6a46a1e13406312af0b72c)