Trailing '/' throws error

The error is seen when running against some keystone versions (details in the
bug description).

The documented way for listing services in keystone doesn't have the trailing
'/': http://docs.openstack.org/api/openstack-identity-service/2.0/content/GET_listServices_v2.0_OS-KSADM_services_Service_Operations_OS-KSADM.html

Additionally all the other API calls in the same file adhere to this
standard.

Change-Id: If3c13b2c46c30232071486ef8cc15492882417f9
Closes-bug: 1300397
diff --git a/tempest/services/identity/json/identity_client.py b/tempest/services/identity/json/identity_client.py
index c95faaa..fe176bf 100644
--- a/tempest/services/identity/json/identity_client.py
+++ b/tempest/services/identity/json/identity_client.py
@@ -219,7 +219,7 @@
 
     def list_services(self):
         """List Service - Returns Services."""
-        resp, body = self.get('/OS-KSADM/services/')
+        resp, body = self.get('/OS-KSADM/services')
         return resp, self._parse_resp(body)
 
     def delete_service(self, service_id):