Mayor Richard Daley's son, whose name and MBA from one of the nation's most prestigious universities would have opened doors to a lucrative career, has instead joined the Army and could be sent off to the battlefields of Iraq or Afghanistan. Patrick Daley, 29, who got his master's degree from the University of Chicago in June, said he "always wanted to find a way to serve ... just like my grandfather and father." He said the Sept. 11 attacks played a role in his decision to enlist in the airborne infantry. "Think of it. It's amazing. I get to serve...