New formula: ruby-install

Closes #20610.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
Ruby 2.0 is no fun for production. Revert default version at BitTorrent to v1.9.3-p392
Gah, direnv 2.0 is written in Go and is now broken. REVERT
Merge branch 'master' of https://github.com/bittorrent/homebrew