Display modal window for preview of the imported data

![inspire - high-energy physics literature database](https://cloud.githubusercontent.com/assets/3083746/4151698/5230e31e-3448-11e4-8894-a7e4885fb1dd.png)
![inspire - high-energy physics literature database 1](https://cloud.githubusercontent.com/assets/3083746/4151697/522d8368-3448-11e4-8fe4-b3efce92d47c.png)
In submission form it is referred as previewModal, and here the class name is ModalPreview. We should stick to one, PreviewModal seems more correct English ;).