grunt: jquery plugins additions

* Adds missing `datepicker.css`, `theme.css` and
  `ui-bg_flat_75_ffffff_40x100.png`.

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>
Reviewed-by: Javier Martin Montull <javier.martin.montull@cern.ch>
search: fix css file path

* File on css/typeahead.js-bootstrap.css has
  the wrong path

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>
Reviewed-by: Javier Martin Montull <javier.martin.montull@cern.ch>