Party for a cause at the fifth annual Global Citizen Festival on September 24th in Central Park. This year’s lineup features headlining shows by Rihanna, Kendrick Lamar, Selena Gomez, Major Lazer, and Metallica. The event also has several high-profile “special guest performances” scheduled from Usher, Eddie Vedder, Ellie Goulding, Yusuf/Cat Stevens, and Chris Martin (who…