Adding repository field to package.json

In order to use via npm install, need repository field in the package.json so this has been added and the readme updated with how to use in this way.
For npm install you can use a gzipped tarball if the thing you are trying to install is not published on the npm registry:
https://www.npmjs.org/doc/cli/npm-install.html

Could easily remove the version number that I've included here and replace with <version> as I was just using the example that I've got in my code.

Hope that makes sense and answers your question?