Make installable using homebrew

[andrewferrier]

https://github.com/caskroom/homebrew-cask/blob/master/doc/CASK_LANGUAGE_REFERENCE.md
https://github.com/caskroom/homebrew-cask/blob/master/CONTRIBUTING.md

[andrewferrier]

Also integrate normalize-filename so the same version used from the command line is the one used for the Finder service.