Migrate index.html example to raf@1.0.0

`raf` was split in two (`raf` and `raf-stream`) before the 1.0.0 release. `raf` is now the actual polyfill, while `raf-stream` is an event emitter which wraps `raf`.

I don't know how the browserify-cdn caching works, but I'm still receiving raf@0.1.3 even after clearing my local IndexDB. Once browserify-cdn starts delivering 1.0.0 the example in `index.html` will stop working (without this fix). The deployment of this fix needs to somehow coincide with the cache expiration of `raf`.

Another solution to this problem (which would sidestep the challenges outlined above) would be to use `raf-stream` instead of `raf`. It's your call, I'm happy to do either (although I do think `raf-stream` is slightly overkill for this example).