gnocchi: remove possible ending / in URL
gnocchi: remove possible ending / in URL

If the URL ends up with a /, then URL are built with 2 /
e.g. POST //v1/foobar and that does not work.

Change-Id: I98e9a0e85e9dd6ae022bbc0543244e533b1307f7

idegtiarov/ceilometer,ityaptin/ceilometer,maestro-hybrid-cloud/ceilometer,eayunstack/ceilometer,fabian4/ceilometer,maestro-hybrid-cloud/ceilometer,openstack/ceilometer,ityaptin/ceilometer,eayunstack/ceilometer,idegtiarov/ceilometer,isyippee/ceilometer,openstack/ceilometer,fabian4/ceilometer,isyippee/ceilometer