add ruby file for 4K YouTube to Mp3 (+1 squashed commit)
Squashed commits:
[2fdf25b] fix Classname

add ruby file for 4K YouTube to Mp3
Merge branch 'master' of https://github.com/giofilo/homebrew-cask

* 'master' of https://github.com/giofilo/homebrew-cask:
  fix Classname
  add ruby file for 4K YouTube to Mp3

Conflicts:
	Casks/fourk-youtube-to-mp3.rb