Add quotas client + tests, for the admin api

Change-Id: I7743f97b919511dc0c9d06415838ab4c3dfcac33
diff --git a/designate_tempest_plugin/clients.py b/designate_tempest_plugin/clients.py
index 8e83bcf..d042f65 100644
--- a/designate_tempest_plugin/clients.py
+++ b/designate_tempest_plugin/clients.py
@@ -20,6 +20,8 @@
     ZoneImportsClient
 from designate_tempest_plugin.services.dns.v2.json.blacklists_client import \
     BlacklistsClient
+from designate_tempest_plugin.services.dns.admin.json.quotas_client import \
+    QuotasClient
 
 CONF = config.CONF
 
@@ -41,3 +43,4 @@
         self.zone_imports_client = ZoneImportsClient(self.auth_provider,
                                                      **params)
         self.blacklists_client = BlacklistsClient(self.auth_provider, **params)
+        self.quotas_client = QuotasClient(self.auth_provider, **params)