If your favorite uncles dropped in from out of town for a rare visit, you'd probably be surprised if the mood turned somber and they started lecturing you. You'd be downright shocked to find yourself enthralled with the strange turn the evening had taken. That's probably how most people felt in the packed house at First Midwest Bank Amphitheatre in Tinley Park as Crosby, Stills, Nash & Young raged on for three hours Sunday night. The granddaddy of rock's "supergroups," touring for the third time as a quartet since Neil Young rejoined in 2000 after a 26-year absence, wore its...