Add ability to specify jquery-file-upload pasteZone option

[adamgriffis]

This is a pretty specific need to my project, but we had an issue where users were trying to paste content into the page and the jquery file upload plugin was picking up the paste event and putting it into the multiple attachinary fields. There's a param to control the paste behavior on a more fine-grained level, but I had to add support of it into the gem.