Fashion brands are upping the stakes on innovation at London Fashion Week, with Burberry, Topshop, River Island and Hunter all competing to create the most groundbreaking digital platforms to showcase their designs and dial up social media buzz.Burberry has teamed with Japanese social messaging app, Line, known for its cute, emoji-like character stickers. The two companies collaborated to create downloadable stickers of Vogue editor Anna Wintour, Burberry designer Christopher Bailey, photographer Mario Testino and British supermodel Cara Delevingne -- all dressed in the iconic Burberry chec...