I\'m not familiar with Python, NodeJS, NPM or Grunt, but I needed to install it because I want to try out a Github project.
I downloaded NodeJS from node.org and install
Your problem has nothing to do with Python, nor does the project you're trying to work with.
npm install will look for a local package.json file and install dependencies from the list supplied in there. After you clone the project you mentioned, make sure you cd to the location of package.json and try npm install again.