Motivation:
Socks5 proxy supports resolve domain at the server side. When testing
with curl, the SocksServer in example package only works for proxy
request with IP, not with domain name (`--socks5` vs
`--socks5-hostname`). As curl is widely used, it should work with
the example provided.
Modifications:
Passing address and port to the Socks5CommandResponse, so that it
works for curl.
Result:
`curl --socks5-hostname` works as expected.