@gib: Use real data when adding artworks from urls

This adds an endpoint to the local API that merges artwork data given a request of slugs or ids e.g. `/api/artworks?id[]=matthew-abbott-lobby-and-supercomputer`. The client then parses the ids out of the urls that are pasted in and makes this request, pumping the artworks back into the component's state and rendering the artworks.

![cap](https://cloud.githubusercontent.com/assets/555859/4759499/dd16ba38-5ae7-11e4-8a45-c656ad6f5624.gif)

`async.parallel`!? cool