deposit: fix of field messages

* Fixes field info/warning/error/success messages, according to
  Bootstrap's newest documentation; also, adds a variable that prepares
  for future changes on the 'error' field name.

* Updates to $.map() for better browser integration.

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>
Reviewed-by: Javier Martin Montull <javier.martin.montull@cern.ch>