Right now curl is a dependency of whole libbitcoin but curl is used just
to discover the public ip of the host running libbitcoin.

I think it would be nice to get rid of it.
Apart from that, none of the services used to get the public ip
(whatismyip.org and checkip.dyndns.org at the moment) do support https,
so it's easily replaceable by a socket and a GET request.

Regards,
Pablo.