base: jquery-multifile source update

* Moves jquery-multifile source to Github to avoid error on
  installation.

Signed-off-by: Javier Martin Montull <javier.martin.montull@cern.ch>
groups: API addition

* Adds API and REST API for the groups.

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