deposit: arXiv/DOI/ISBN fields import validation

* Allow arXiv/DOI/ISBN import only if it's well formatted.

* Adds tooltip to import button.

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>
deposit: fix to message box multiple append

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>