Update package.json

I've given the npm package.json manifest a long overdue rewrite.

After pulling these in I'd strongly recommend taking 5mins to delete the existing node_modules directory, run `npm cache clean` then freshly install with `npm install` as I experienced a few problems during development due to npm's cached version.

Apologies for any disruption that causes - this really needed reworking to be a proper "grown-up" package.json file moving forward :)