Identifier 'PropTypes' has already been declared

We use contextTypes so we have to import PropTypes:

```
ScreenHomepage.contextTypes = {
locale: PropTypes.string,
colors: PropTypes.object,
};
```

However, when using the plugin the build fails with:

> ./layout_modules/screen-homepage/ScreenHomepage.js 422:7
> Module parse failed: Identifier 'PropTypes' has already been declared (422:7)
> You may need an appropriate loader to handle this file type.
> | };
> | export default ScreenHomepage;
> > import PropTypes from "prop-types";

This is probably due to the fact the plugin auto adds the PropTypes import.

Is there an option to tell the plugin not to import PropTypes if the import exists?