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
Merge "Trailing '/' throws error"