George Saunders, author of “In Persuasion Nation,” spoke on Feb. 23 at the University of Massachusetts in the Student Union Ballroom. Over an hour and a half, the thin, bearded Chicagoan told the standing-room audience something like his life story. In his words, he set out to describe “the way art actually works.” As a writer, he did this by telling stories. As a funny writer, those stories tended to put him as the butt of the jokes.