Create a GitHub Release to store our VM binary files

Once we land #83, we're going to have a set of binary files we need to download/deploy every time we build the site on Travis, including:

* [seabios.bin](https://github.com/copy/v86/blob/master/bios/seabios.bin?raw=true)
* [vgabios.bin](https://github.com/copy/v86/blob/master/bios/vgabios.bin?raw=true)
* and our new `v86-linux.iso` that buildroot creates.

The GitHub docs suggesting [creating a Release](https://help.github.com/articles/creating-releases/) when you have binary files like this. I also notice that [Travis can auto-deploy GitHub Releases](https://docs.travis-ci.com/user/deployment/releases/).

So we should figure out how to do this properly. Can we somehow automate this? Or do we need to manually create a release every time we update the VM binary files (I don't think it will be often)? We could also consider moving the buildroot stuff, Docker stuff, and binary files to a new repo that only does this.