ADMIN : add EDIT and INFO button for users in action column in GROUPS tab

[gvincke]

When editing a group, in the column "action" of the list of users, it could be very usefull to have the "edit" and "info" buttons for all users. Actually when i see a user, i have to copy his login name, gi to users tab, put the login in the search tab, and then click on edit or info. Too time consuming ;-)

[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.