Bug 1089486 - [NFC] Disable NFC toggle in settings during NFC HW change,  r=arthur.chen, r=gweng

https://bugzilla.mozilla.org/show_bug.cgi?id=1089486
Sure, will do this. I'll need to rebase the patch since promises use in the API has landed. Do you have some other remarks, or do you want me to fix this, rebase and ask once more for the review?