I ended up installing all grunt dependencies manually.
npm install time-grunt npm install load-grunt-config

I ended up installing all grunt dependencies manually.
npm install time-grunt npm install load-grunt-config
and then all modules listed here:
![enter image description here][1]

[1]: http://i.stack.imgur.com/48OVK.png
Note: you can install all of the dependencies in the photo above in one go with `npm install`.
Finally I ran the `grunt` command and it worked!