fix severe fd leak in stack

Signed-off-by: allencloud <allen.sun@daocloud.io>
(cherry picked from commit 0af04b613220060ef1fc21ca2f1d551f8f868af8)
Signed-off-by: Tibor Vass <tibor@docker.com>

api/client/stack/opts.go

@@ -35,6 +35,7 @@ func loadBundlefile(stderr io.Writer, namespace string, path string) (*bundlefil
 	if err != nil {
 		return nil, err
 	}
+	defer reader.Close()
 
 	bundle, err := bundlefile.LoadFile(reader)
 	if err != nil {