It took six years for Redbox to cross the one billion discs rented mark, but clearly the pace is picking up as it's taken only 18 months to duplicate the feat. Sure, two billion is no 25 billion, but the red kiosk company isn't just going to share the love with the milestone maker who just wanted to check out Ryan Gosling in Drive. Thursday, all customers can pick up a free DVD rental (Blu-ray and