Social media can’t provide what social change has always required.SEYMOUR CHWAST At four-thirty in the afternoon on Monday, February 1, 1960, four college students sat down at the lunch counter at the Woolworth’s in downtown Greensboro, North Carolina. They were freshmen at North Carolina A. & T., a black college a mile or so away. “I’d like a cup of coffee, please,” one of the four, Ezell Blair,