BOSTON (CBS4) Bomb sniffing dogs went bag by bag, checking for explosives before they were put back in an American Airlines flight destined for Miami. Security officials unloaded and rechecked each luggage piece aboard an American Airlines flight headed to Miami from Boston after a bomb scare broke out Wednesday afternoon. Authorities found nothing suspicious on the plane that was emptied and moved to an isolated area at Logan International Airport after a written bomb threat was found on board. The American Airlines plane and luggage was searched Wednesday by police and a bomb-sniffing dog. (snip) During the preboarding process,...