Fix sorting/filtering in admin list
Fix sorting/filtering in admin list

After adding/removing an admin the order of the list was random-ish
instead of alphabetical. Also, deleted users were not excluded in the
query.

mic4ael/indico,ThiefMaster/indico,DirkHoffmann/indico,ThiefMaster/indico,pferreir/indico,pferreir/indico,DirkHoffmann/indico,OmeGak/indico,mvidalgarcia/indico,indico/indico,pferreir/indico,mic4ael/indico,mic4ael/indico,mvidalgarcia/indico,indico/indico,mvidalgarcia/indico,mic4ael/indico,OmeGak/indico,indico/indico,indico/indico,DirkHoffmann/indico,DirkHoffmann/indico,ThiefMaster/indico,OmeGak/indico,pferreir/indico,mvidalgarcia/indico,ThiefMaster/indico,OmeGak/indico