Py3: do not use dict.iteritems()
    
    Py3 does not support iter* methods, this commit replaces 2 occurencies
    of iteritems() to items(). The dictionaries there are not big, this is
    sufficient we do not need to use six.
    
    https://fedorahosted.org/freeipa/ticket/5623
    
    Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>