deposit: support of multiple subjects

* Allows to select multiple subjects using the Bootstrap
  multiselect library for the frontend.

NOTE: run `grunt` to copy the external libraries.

Signed-off-by: Georgios Kokosioulis <georgios.kokosioulis@cern.ch>
Merge pull request #8 from giokokos/multiple-subjects

deposit: support of multiple subjects
deposit: translated title field

* Adds translated title field if the selected language isn't English.

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>
deposit: language underneath title

* Moves both the language and the translated title fields underneath the main
  title field.

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>
Merge pull request #6 from pedrogaudencio/deposit-translated-title

deposit: translated title field
deposit: usability enhancement of import

* Improves the usability when importing Identifiers
  by displaying a spinner when the AJAX call ends.

* Passes JSHint checks.

* Separated from fillform.js file.

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