Add the commit hash to zsh and oh-my-zsh on Ubuntu linux

If you haven't heard of it zsh is a bash alternative and oh-my-zsh is an awesome set of customizations.  Now using just agnoster with powerline fonts you can get this result at the terminal which is great!

See here for example: https://github.com/agnoster/agnoster-zsh-theme

Now what I wanted was to also show the commit hash, so I needed to edit the theme file for agnoster, and here is the result.