deposit: plupload improvements

* Allows autoupload on file selected.

* Fixes a bug when deleting a file right after uploading it.

* Fix in Blueprint url endpoints for upload urls.

* NOTE Removes check for duplicated file. To enable it, add
  filters: { prevent_duplicates: true } to plupload configuration.

Signed-off-by: Javier Martin Montull <javier.martin.montull@cern.ch>