React 16 Import Error

It looks liker react-hotkey is not compatible with the current release candidate of React 16 (16.0.0-rc.3). On application startup I get the following error:

```
Uncaught Error: Cannot find module 'react-dom/lib/SyntheticKeyboardEvent'

...\node_modules\react-hotkey\index.js:2:30)
```

It looks like this module doesn't exist in that location any more in react-dom. It looks like it is now only defined in react-dom.development.js and it is not in module.exports, make it difficult to access. Given that this was a private method, I'm not sure what part of react/react-dom should be used for an updated keyboard event handler.