Zoom feature for plop viewer

I've updated d3.js to the latest version, did some cleanup and added a zoom feature. Now everything renders in the middle of the screen and you are able to zoom into into the nodes that interest you. UX feels much better now.
Can we load this from somewhere else instead of shipping our own copy?  E.g. `http://d3js.org/d3.v3.min.js` or `//cdnjs.cloudflare.com/ajax/libs/d3/3.4.10/d3.min.js`