Hyper DNS Resolver

NetworkConnector to allow using a custom DNS server with SRV records in Hyper.

Below shows a quick example of how this library can be used (you will need to have SRV records setup for the domain to query):

``` extern crate hyper_dns; extern crate hyper;

use std::net::ToSocketAddrs;

fn main() {

let dns_addr: std::net::SocketAddr = ("127.0.0.1", 8600).to_socket_addrs().unwrap().next().unwrap();

let client = hyper::client::Client::with_connector(
    hyper_dns::DnsConnector::new(dns_addr, hyper::net::HttpConnector));

client.get("http://test.service.consul/").send();

} ```