Async support?

[StevenLu2004]

Hi! Thank you so much for MCRcon. I've been using it for more than a year and I couldn't be more satisfied with it. It's just that I'm recently implementing an http server that uses asyncio and also needs an Rcon, so I just want to check with you whether there currently is a plan for async support. I'm currently implementing a class AioMCRcon for my own purpose, based on your 0.6.0 release because I forgot to update, and I'm also wondering if I can later make a PR to your repo.

[unexceptable]

I'm more than happy to review and add this to the repo. We just have to make sure that non-asyc support is untouched. So any code that can be shared we should between the two, but quite likely we need to make this as two different client classes (MCRcon and AioMCRcon).