NOOO!!!!! Your baby is likely to catch it from you anyways, whether you're nursing or not. He won't get it from your milk, but from you breathing on him. Once your body has produced antibodies to fight it off, he will get those antibodies through your milk, to help him fight it off if he does catch it.
No!! You should keep nursing. Your baby will get your antibodies, not your cold. The baby would get sick from your breathing on him/her. Plus, your milk would likely dry up if you went that long without nursing.