Navigate to the root of your theme in Terminal.
1. Installing grunt globally
npm install -g grunt-cli
I ended up preceding this with
sudo to get it working.
2. Move Gemfile, Gruntfile.js and package.json to your theme's root
|# This is a template .gitignore file for git-managed WordPress projects.|
|# Fact: you don't want WordPress core files, or your server-specific|
|# configuration files etc., in your project's repository. You just don't.|
|# Solution: stick this file up your repository root (which it assumes is|
|# also the WordPress root directory) and add exceptions for any plugins,|
|# themes, and other directories that should be under version control.|
|# See the comments below for more info on how to add exceptions for your|