Support a custom download bucket when downloading rubies
Merge pull request #27 from lucasmazza/custom-download-bucket

Custom bucket to download rubies
Use the same environment variables used on puppet-homebrew

See
https://github.com/boxen/puppet-homebrew/blob/2a5183acff6b9ee8a476c14b7bfc3361fdd5daaa/files/boxen-monkeypatches.rb#L17-18