In celebration of its 20th anniversary Cirque du Soleil Las Vegas is offering the fans a rare glimpse behind the curtain with the return of its Cirque Week series of events. The fourth year of the annual celebration will run from November 9-16, during which each of the Strip’s eight resident shows will host a series of events ranging from backstage access, performance classes, ticket packages and more. Options include a live fire demonstration from the inferno acts of “O,” choreography lessons from “Michael Jackson One” and an up-close look at the intricate Thierry Mugler costumes from “Zumanity.” Customizable ticket…