Reveal modal: Multiple opened

In my app (marksexpress), I have implemented a wysiwyg editor (summernote-foundation). In admin mode the edit form has been implemented through a modal box, however the editor also uses the modal boxes. So when inserting an image, the editor modal box would be closed. This patch adds an option that allows previous modals to remain open.
![12-24-2014 8-51-49 am](https://cloud.githubusercontent.com/assets/1153495/5548538/3b3766e8-8b4a-11e4-8c34-9997303b207b.jpg)
![12-24-2014 8-53-00 am](https://cloud.githubusercontent.com/assets/1153495/5548543/4b7ac270-8b4a-11e4-8949-28ab7875dfee.jpg)