deposit: enhancements of form

* Adds tooltip feedback when proceedings information box is
  disabled.

* Drops smoothscroll and changed to slideDown() for consistency.

* Clears the form elements before import.

* Highlights the imported fields.

Signed-off-by: Georgios Kokosioulis <georgios.kokosioulis@cern.ch>
deposit: dynamic url field

* Makes the url field repeatable.

Signed-off-by: Georgios Kokosioulis <georgios.kokosioulis@cern.ch>