ABC News' Matthew Jaffe Reports: Sen. Joe Biden, D-Del., on Sunday guaranteed that if elected, Sen. Barack Obama., D-Ill., will be tested by an international crisis within his first six months in power and he will need supporters to stand by him as he makes tough, and possibly unpopular, decisions. "Mark my words," the Democratic vice presidential nominee warned at the second of his two Seattle fundraisers Sunday. "It will not be six months before the world tests Barack Obama like they did John Kennedy. The world is looking. We're about to elect a brilliant 47-year-old senator president of the...