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

ceilometer/dispatcher/gnocchi_client.py

@@ -216,7 +216,7 @@ class GnocchiSession(object):
 
 class Client(object):
     def __init__(self, url):
-        self._gnocchi_url = url
+        self._gnocchi_url = url.rstrip("/")
         self._ks_client = keystone_client.get_client()
         self._session = GnocchiSession()