Added attrs to permission when target is group or filter
    
    Option to set attributes in permission was missing for target 'group' and 'filter'.
    
    Attribute_table_widget with type=group is shown for target=group.
    
    For target=filter a multivalued textbox is shown. This is because UI can't predict what type will the result of the filter be. In future it can be extended by interactive attribute selector to help user find what he wants to enter.
    
    Mutlivalued widget was modified to show undo button for new entries even if show_undo is false. It is useful in adder dialog to indicate that user added something and to enable it reversal.
    
    https://fedorahosted.org/freeipa/ticket/2372