Bad endpoint URL for ceilometer set by Ansible playbook

Ceilometer's endpoint URLs, set into Keystone, have the wrong format http://service-host:8777/v2/tenant_id. 

According to http://docs.openstack.org/developer/ceilometer/install/manual.html#configuring-keystone-to-work-with-api, it should be http://service-host:8777/ . This generates an error on Horizon dashboard: the "ressource usages" panel is no more available.
