ctf tools shouldn't add blank labels
SmartOS bug http://smartos.org/bugview/OS-7653
Today, when no label has been requested we end up creating a label section with an empty name. There's really no reason for such a label to exist. We should make this explicit and not have such empty labels when nothing has been passed in. If a user desired, they could still create a valid label with an empty name, though that feels of questionable utility.