If you didn’t think that Roc Nation was serious, you better ask somebody.  It’s been reported that just two months after being born, the company run by Jay-Z is going to be signing NBA star Kevin Durant to its roster of superstars.  This is right after picking up Skylar Diggins, the #3 pick in the WNBA draft, as well as Yankees second baseman Robinson Cano.   This week, Kevin dropped…