std::net::lookup_host is deprecated

It looks like `std::net::lookup_host` has been [deprecated](https://github.com/rust-lang/rust/issues/27705) and it is advised to use the [ToSocketAddrs](https://static.rust-lang.org/doc/master/std/net/trait.ToSocketAddrs.html) trait. This is causing me some issues compiling for windows. I will try and submit a PR but I am very new to rust!

