Bower support for non-AMD environments

This repository is listed as the defacto standard `requestAnimationFrame` package on bower. I think most users would expect to `bower install requestAnimationFrame` and get something that works with both AMD and non-AMD configurations. Any package that is AMD only, is typically listed with a `-amd` suffix. And since this is a pretty straight forward polyfill that intentionally modifies the environment, supporting non-AMD configurations is simple.