Issue 92 - display_attr() should return str not bytes in py3
    
    Bug Description: display_attr method of mapped object returns
    bytes in python3. Since we use this function to display display
    data to the end user we don't want this.
    
    There is also a bug in get_attr_vals_type() methods. These
    methods call a non-existing function due to a typo.
    
    Fix Description: Call get_attr_valus_utf8 instead of get_attr_vals
    from within display_attr method. Also fix the bug with the
    get_attr_vals_type by correcting the method's name.
    
    https://pagure.io/lib389/issue/92
    
    Author: Ilias95
    
    Review by: wibrown (Thanks!)