A few weeks ago, WGCI announced the headliner for their 2011 annual holiday concert, Big Jam, and today they unleashed the full lineup. Joining R. Kelly is Young Jeezy (with Freddie Gibbs no doubt in tow), L.E.P. Bogus Boys, Future, Jacob Latimore and Mindless Behavior. Big Jam 2011 takes place on December 23 at the…