TThe long-running Music Midtown festival at Piedmont Park in Atlanta, scheduled for Sept. 17-18 with headliners My Chemical Romance, Future, Jack White and Fallout Boy, has been called off, according to a statement issued by festival organizers. The likely cause, industry sources tell Billboard, are recent changes to Georgia gun laws that prevent the festival from banning guns on to the publicly owned festival grounds... … While owner Live Nation didn’t provide any additional details for the cancellation, pro-gun rights groups had been emailing and posting comments of the festival’s social media page for several months, hinting at potential legal...