Retail veteran Ron Johnson joins BI Live.Bloomberg / GettyApple Stores have been a huge win for the brand. What's the secret of their success?Former Apple exec Ron Johnson explains, and shares what's working — and what's not — in retail today.Scroll down to join our live Q&A on Thursday at 1:30 p.m. ET.When Ron Johnson joined Apple in 2000, conventional wisdom said the internet would soon make physical stores obsolete.Johnson thought otherwise.I…