Fix profile picture upload and delete
Fix profile picture upload and delete

This allows administrators to upload and delete the profile picture for
other Indico users.

DirkHoffmann/indico,ThiefMaster/indico,indico/indico,pferreir/indico,ThiefMaster/indico,indico/indico,pferreir/indico,indico/indico,DirkHoffmann/indico,DirkHoffmann/indico,indico/indico,pferreir/indico,pferreir/indico,DirkHoffmann/indico,ThiefMaster/indico,ThiefMaster/indico