Pass socket to greedy_stream::Protocol::accepted

[ebarnard]

This allows a protocol to get details of the underlying stream it is connected to.

e.g.

trait IpStream {
    fn peer_addr(&self) -> io::Result<SocketAddr>;
    fn local_addr(&self) -> io::Result<SocketAddr>;
}

impl IpStream for ::mio::tcp::TcpStream {
    fn peer_addr(&self) -> io::Result<SocketAddr> {
        ::mio::tcp::TcpStream::peer_addr(self)
    }

    fn local_addr(&self) -> io::Result<SocketAddr> {
        ::mio::tcp::TcpStream::local_addr(self)
    }
}

impl<T: IpStream, C, H: Handler<C>+Send> Protocol<T, C> for Client<C, H> {
    fn accepted(conn: &T, _ctx: &mut C) -> Self {
        let local_addr = conn.local_addr();
...

[tailhook]

Looks fine. Thanks!