Does not build with React 16

I'm trying to use this library with [react-static](https://github.com/nozzle/react-static) and I'm getting the following error on build:

```
Failed to rebuild.
./node_modules/reactdown/lib/runtime.js
Module not found: Can't resolve 'react/lib/merge' in '/path/to/project/node_modules/reactdown/lib'
```

In my _MarkdownPost.js_ component I am using it like this:

```
import React from 'react'
import { getRouteProps, Link } from 'react-static'
import reactdown from 'reactdown'

export default getRouteProps(({ post }) => {
const Markdown = reactdown(post.body)

return (

I believe the issue is caused by React 16 changing some internals used by this library. The version of `react` used is **16.1.0** and `reactdown` **0.8.0**. Can anyone confirm? Is there a work-around or plans to update this library?