deposit: addition of holding pen

* This task adds the deposition to the Holding Pen so it gets approved
  or rejected by an administrator.

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>
Reviewed-by: Javier Martin Montull <javier.martin.montull@cern.ch>
One blank line is needed before and after the comment.