[CDN Request] Supply minified version to unpkg, or latest releases to cdnjs

The currently recommended CDN service appears to be unpkg.com. However, it appears the [build folder](https://unpkg.com/react-motion@0.5.0/build/) (for the latest release at least) does not include a minified version of react-motion. It would be great to have this as an available external resource.

Similarly, it appears that cdnjs.com [only has version 0.0.3 available](https://cdnjs.com/libraries/react-motion). I'm not sure if there was a conscious decision to move away from CDNjs, or if their API stopped scraping for some reason, but this would also be an awesome resource to have at our disposal.