py3: use ConfigParser instead of SafeConfigParser
    
    DeprecationWarning: The SafeConfigParser class has been renamed
    to ConfigParser in Python 3.2. This alias will be removed in
    future versions. Use ConfigParser directly instead.
    
    https://fedorahosted.org/freeipa/ticket/4985
    
    Reviewed-By: Jan Cholasta <jcholast@redhat.com>
    Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>