deposit: removal of unused argument in form js

Signed-off-by: Kamil Wieslaw Neczaj <kamil.neczaj@cern.ch>
deposit: fix for validation before import.

* Improves TaskManager to use deferred objects better.

* Adds validate() function making a server-side validation
  in background.

Signed-off-by: Kamil Neczaj <kamil.neczaj@cern.ch>