Update to file fields

* Fixes problem with uploading with the advanced fields (See
https://github.com/rilwis/meta-box/issues/296 )
* Uploading multiple files in `file_advanced' and `image_advanced` now
takes one ajax call instead of one per file
Updated jQuery Validation plugin

old version had issues with `range` field
Merge pull request #297 from funkedgeek/master

Image advanced fixes, update to validation