Handling contact addresses

[rayankans]

The ContactAddress interface used to rely on the PaymentAddress interface which has since been dropped. This raises a few questions:

• Is this the right spec to define addresses?
• Should the current interface be changed to have closer HTML/autocomplete alignment?

[marcoscaceres]

• Is this the right spec to define addresses?

It's as good an any.

• Should the current interface be changed to have closer HTML/autocomplete alignment?

That might be good, but it really depends on how much implementer appetite there is for renaming/refactoring things.

I think we should maybe just provide a non-normative mapping in the spec for now... if we start seeing people complain, we can look at renaming things.