[improvement] Don't show payment method "fiat-tap-to pay" when wrapper-app isn't used #241

AS IS: when I use the shared TPOS on my mobile browser, I can't accept fiat payments using tap2pay. However this option is visible when enabled in the TPOS config.

TO BE: Don't show the fiat tap2pay payment method when it's not supported (f.e. when the TPOS wrapper app isn't used)