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
Can this test be modified to do something more substantial than e.g. `--version` or `--help`? See `cmake.rb` for an example of an application formula with a good test and `tinyxml2.rb` for an example of a library formula with a good test. Thanks!