Between this weekend’s Memorial Day summer kickoff and the impending London Olympics, ‘tis the season for getting in shape. For Londoners, getting fit is about to get more fashionable with the launch of the first standalone Adidas by Stella McCartney shop, opening Saturday. The 800-square-foot, two-story shop will be located right next to the designer’s main store on Fulham Road in the Brompton Cross area. Along with the Stella McCartney for Adidas line, the store will also carry replicas of the McCartney-designed Olympic uniforms for Team Great Britain.