deposit: plupload filter option addition

* Adds filters to plupload settings in order, for example, to limit
  the mime types allowed.

Signed-off-by: Javier Martin Montull <javier.martin.montull@cern.ch>
deposit: plupload error div selector addition

* Adds .upload-errors class to plupload.js to show errors related to
  the uploader.

Signed-off-by: Javier Martin Montull <javier.martin.montull@cern.ch>