Added VRChat Avatar Unity Package

I received an email from someone trying to get the model into VRChat, so I went ahead and completed most of the steps myself. To get the model into the game, you should only need to follow the instructions in this video (you'll need Unity 5.6.3p1 and a VRChat account, but it's very simple). I can't test it myself at the moment, so please let me know of any issues (or adventures) via the discussion board. :)

Note: When opening the VRChat SDK in Unity, it warned me that I was using the wrong version of Unity (I had simply downloaded the latest version available for Arch Linux). I didn't get any actual error messages while following the tutorials, so hopefully this didn't affect anything.