Instead of having an array called STARTTLS_PORTS, with linear lookup for
membership, defined SPECIALIZED_FUNCS, mapping port numbers to
negotiation functions. This make sit a little easier to add other SSL
negotiation mechanisms, like HTTP Upgrade.
socket:connect(host.ip, port.number)
socket:connect(host.ip, port.number, port.protocol)
to this:
socket:connect(host, port)
connect can take host and port tables now, and the default protocol is
taken from the port table if possible.
