Assign options.Err in "set image"

There is a usage of options.Err in a Printf, but this option is never set.
This patch passes the stderr into the command and assigns the option correctly.

pkg/kubectl/cmd/cmd.go

@@ -249,7 +249,7 @@ Find more information at https://github.com/kubernetes/kubernetes.`,
 				NewCmdCreate(f, out),
 				NewCmdExposeService(f, out),
 				NewCmdRun(f, in, out, err),
-				set.NewCmdSet(f, out),
+				set.NewCmdSet(f, out, err),
 			},
 		},
 		{