Fix domain unless condition

Domain name is uniq, we have grep logic around checking if
domain exists which have potentials bugs when have two domains
and one is substring from another.

This patch fixes this issue by using domain show command.

Change-Id: I18ca4c990f7f3790eb32ae7764a1336f5a541556
diff --git a/keystone/server.sls b/keystone/server.sls
index 7ce971a..02548d0 100644
--- a/keystone/server.sls
+++ b/keystone/server.sls
@@ -232,7 +232,7 @@
             --os-endpoint {{ server.bind.get('private_protocol', 'http') }}://{{ server.bind.private_address }}:{{ server.bind.private_port }}/v3
             --os-token {{ server.service_token }}
             --os-auth-type admin_token
-            domain list | grep " {{ domain_name }}"{% endif %}
+            domain show "{{ domain_name }}"{% endif %}
     - shell: /bin/bash
     - require:
       - file: /root/keystonercv3