The late, great Jimmy Buffett was honored last night by an assortment of his many friends and admirers in an all-star tribute concert at the Hollywood Bowl.    Keep the Party Going, as the show was billed, took place 7-months after Buffett died from skin cancer in September at age 76.   Among the many acts who performed:   Paul McCartney, the Eagles, Jon Bon Jovi, Jackson Browne, Brandi Carlile, Kenny Chesney, Eric Church, Sheryl Crow, Zac Brown, Jack Johnson, Pitbull and members of Buffett’s longtime Coral Reefer Band.    Here’s Paul McCartney