Ghost members - modifications in sysdb
    
    Deleted sysdb_add_fake_user():
    This function is no longer used.
    
    Modified sysdb_add_user():
    When user object is added to sysdb, it is important to iterate over all
    groups that might have its name or any of its aliases as ghost member
    and replace this ghost membership by a real one. This will eliminate
    duplicite memberships.