Ticket 67 - get attr by type
    
    Bug Description:  In python 3 the change to utf8 has caused us some
    difficulty. As a result, to help ease this, we need to be able to retrieve
    attributes by types in DS
    
    Fix Description:  In mapped object, add the ability to request types
    for searches when we perform them.
    
    https://pagure.io/lib389/issue/67
    
    Author: wibrown
    
    Review by: ilias95, spichugi (Thanks!)