It’s a Saturday night at the UIC Pavilion, and Jaclyn Stacy is cheering her team. As the Ramones boom from the speakers — “Hey, ho, let’s go!” — the faithful fans of the Windy City Rollers roller derby league are watching a game between the Fury and Hell’s Belles, clapping and cheering and screaming for their favorite skaters. “We have to kill ’em now!” shouts one fan from behind the Fury bench. “FUUUUURYYY! Let’s go Fury!” Stacy, the …