deposit: ckeditor sanity check

* Avoid error if deposit form is not using ckeditor in any field.

Signed-off-by: Javier Martin Montull <javier.martin.montull@cern.ch>
deposit: for loop rewrite to $.each

Signed-off-by: Javier Martin Montull <javier.martin.montull@cern.ch>
Reported-by: Yoan Blanc <yoan.blanc@cern.ch>
tags: REST API addition

* Creates API for tags, in order to have a reusable API
  both for restful API and views probably.

* Refactors tags REST API in order to use the new tag API.

* Tests the tags REST API.

Signed-off-by: Konstantinos Kostis <konstantinos.kostis@cern.ch>