(Review by special DCist contributor Justin Kielsgard) Despite the debilitating D.C. humidity, summer is a time when people live in the open air. It’s a time when restrictions are looser, when possibilities seem fuller and closer. And no band represents the idea of possibility or freedom better right now than the eclectic 12-piece ensemble Pink Martini. For about two hours on Monday night the 9:30 Club was transformed from Hipster Haven to Continental Cabaret. In…