Any plans for async DNS

[tailhook]

Hi,

Any plans to integrate asynchronous DNS resolver into this crate? I'm looking forward to port rotor-dns to futures, and I'm wondering should I contribute to this library or create a separate one.

[sbstp]

I didn't plan to do it myself, but if you wish to contribute one I'll gladly take it. If you have issues with the current API, just let me know and we'll find a solution.