Adding DeleteResult for volumes.Delete
diff --git a/openstack/blockstorage/v1/volumes/results.go b/openstack/blockstorage/v1/volumes/results.go
index ca322d1..2e94288 100644
--- a/openstack/blockstorage/v1/volumes/results.go
+++ b/openstack/blockstorage/v1/volumes/results.go
@@ -59,6 +59,11 @@
 	commonResult
 }
 
+// DeleteResult contains the response body and error from a Delete request.
+type DeleteResult struct {
+	commonResult
+}
+
 // ListResult is a pagination.pager that is returned from a call to the List function.
 type ListResult struct {
 	pagination.SinglePageBase