feat(build*): add CoreOS production image building

This will create a CoreOS production image and support it with the tools
like image_to_vm.sh and build_image.
chore(build_container): delete

This tool was a bit of a hack and isn't really used. Delete it.
fix(image_to_vm.sh): forward fewer ports

we disabled systemd-rest for now so don't tell people to forward all of
those ports.