Users lists improvements

Improvement proposition : a feature to set the way admin wants to display the list of users, or groups. Configuration choices between :

• name of the wiki page
• first name and last name field
• user name field
• (to be completed)

Use case recently encountered :
We have set a XEM interfaced with webservices to populate the wikis.
When viewing the lists in XWikiGroups, each item was displayed with the ID number used by the webservices. Then the list was unusefull to the viewer...