Support for using multiple inputs for one field

[dcardosods]

Card supports using multiple inputs for one field. Wouldn't it be a good idea to support it here?

Maybe creating additional directives, e.g. cardFirstName, cardLastName, cardMonthExpiry, cardYearExpiry...

[lnpbk]

@dcardosods A little late, but I've added the ability to do this with the card's expiry date in my PR.