preserve localStorage for SIM logout (bug 1042381)

@muffinresearch this is WiP but can you think of why we needed to clear localStorage? I think I was the one who added it to Webpay, heh, but I can't think of why we need it. Even for PIN resets I don't think we need it. BTW, does the PIN reset flow work for you? Even without this patch I couldn't get it to work. It stalled on 'Connect to Persona' after I pressed the Continue button on the reset page.