The new US passport was designed under a guy who once kept Airbnb alive by selling cereal. Back in 2008, Joe Gebbia and Brian Chesky were buried in credit card debt and no investor would touch the idea of strangers sleeping on air mattresses in your apartment. So the two design school grads printed collector's edition cereal boxes, Obama O's and Cap'n McCain's, and sold them for $40 each during the election. They raised about $30,000. That money kept the company breathing long enough to get…