"export from" is not handled

Hi, I had some trouble with one particular file today that looked like this:

```js
export { default as A } from 'dir/a';
export { default as B } from 'dir/b';
export { default as C } from 'dir/c';
```

It turns out that this plugin does not handle the `export from` syntax and leaves the paths as they are.

I'd like to fix that, so expect a PR soon 🙂 