Sample 18 - Add react hot loader support

Add react hot loader support based on:

[https://github.com/wmaurer/react-hot-boilerplate-ts/blob/master/src/App.tsx](https://github.com/wmaurer/react-hot-boilerplate-ts/blob/master/src/App.tsx)

[http://blog.novanet.no/hot-loading-react-in-typescript/](http://blog.novanet.no/hot-loading-react-in-typescript/)
