Slash (Guns N’ Roses), Nancy Wilson (Heart), Robert Randolph, Liz Warfield, and an L.A. all-star band will be performing at the Greater Los Angeles Zoo Association’s 2018 Beastly Ball and fundraiser on May 19. The event, which will commemorate National Endangered Species Day, will also honor Jack Hanna and feature the unveiling of Ruben Rojas’…