ADMIN : add "refresh" button in groups

[gvincke]

Usercase : 1/ I create a user 2/ I go to the "group" tab to add this user to a group 3/ User is not in the user select list => must do a manual refresh and then lost the group selection, etc.

Is it possible to add a "refresh button" to refresh the user list like in some others area of cytomine to simplify this procedure ?

Thanks

[geektortoise]

The group feature need to be refactored. I keep the ticket open (removing v2 milestone) as it will be used to design the refactoring.