Jerry Garcia’s 75th birthday was celebrated by one and all at Red Rocks over the weekend and one of Garcia’s bandmates, Bob Weir, performed with his Campfire Band along with special guest (and Dead & Co. bandmate) John Mayer for an extended set. The ensemble, which also features The National’s Scott and Bryan Devendorf as well as Josh Kaufman, Steve Kimock and Jon Shaw, dug into a lengthy…