Add /volume to block-storage endpoint

The block-storage endpoint was added to the catalog, but in the suburl
case it was not added with the /volume suburl. This leads to find it and
attempting to use it but not being able to because it's mis-formed.

Needed-By: https://review.openstack.org/545117
Change-Id: I84721c8ae637417e4b01be9e546ff77c250fc149
diff --git a/lib/cinder b/lib/cinder
index 96a7d5b..75486ad 100644
--- a/lib/cinder
+++ b/lib/cinder
@@ -372,7 +372,7 @@
             get_or_create_endpoint \
                 "block-storage" \
                 "$REGION_NAME" \
-                "$CINDER_SERVICE_PROTOCOL://$CINDER_SERVICE_HOST/"
+                "$CINDER_SERVICE_PROTOCOL://$CINDER_SERVICE_HOST/volume/"
 
             get_or_create_endpoint \
                 "volume" \