Add helios package

This package supplies the command line executable jar for
Helios, a Docker container orchestration platform developed
and open-sourced by Spotify.

https://github.com/spotify/helios
@mikemcquaid I think I've found a nice way to do this.

I found the `write_jar_script` function that you guys provide and which many other formula use. The function allows for jvm options which other people have also found useful like https://github.com/Homebrew/homebrew/blob/master/Library/Formula/calabash.rb.

Let us know if this works for you. Thanks