[registrars] Using IANA IDs

[Eric Brunner-Williams in Portland Maine]

Jay,

This is a good point. The set of code points "current" at any point in
time at the IANA registry doesn't account for registry-transitional
"registrars", nor can it account for registrars no longer "current"
(ICANN accredited) -- rather like the .su country code.

I suspect we need something more.

Eric