Update React, add module system and tests

I needed a typeahead / autocomplete React component. Yours was a little bit out of date, so I forked it and updated... a few things:

* UMD builds with Browserify
* some tests!
* `onAddToken` and `onRemoveToken` events for Tokenizer
* `customClass` options
* examples showing of `customClass` with [Topcoat](http://topcoat.io)

I would also like to publish this to `npm`, which is the primary reason behind submitting this admittedly large changeset as a pull request. If you're cool with all the changes, publishing to npm would be swell. If not, I'll happily maintain and publish my fork -- just want to give you the right of first refusal :smile_cat: