Believe it or not, it's possible to to be a star within the six seconds of a Vine video -- just ask the likes of Riff Raff or Will Sasso, whose Vines are nearly as popular as their usual work. Social media guru Gary Vaynerchuk is starting up a talent agency, Grape Story, to make sure those celebs are getting paid in more than just likes. While Vaynerchuk isn't naming initial clients beyond co-founde
