Fix: Installation of gitsh
Fix: Installation of gitsh

- gitsh does not install correctly with mac (system) ruby
- gitsh does not install correctly with brew because it uses
  system ruby
- gitsh issues seem to suggest that this problem is a high sierra
  issue https://github.com/thoughtbot/gitsh/issues/329
- Need to install ruby then run the manually install gitsh
- Once all macs are upgraded to mojave, manual install can be
  removed

stephaneliu/dotfiles,stephaneliu/dotfiles