Bower support

It looks like this repo was registered as the main `setImmediate` polyfill on bower. Though it doesn't seem to have a `bower.json`. If you don't know what this is, you may have not of registered it, maybe someone else did.

```
$ bower search setimmediate
Search results:

    setimmediate git://github.com/NobleJS/setImmediate.git
```

I'd love to see this package get a proper bower config file. But if you have no interest, I could setup a mirror under https://github.com/components and maintain it myself.

/cc @domenic