Added permission field to delegation
    
    Permission field is missing in delegation so it can't be set/modified.
    
    It was added to delegation details facet and adder dialog.
    
    The field is using checkboxes instead of multivalued textbox because it can have only two effective values: 'read' and 'write'.
    
    https://fedorahosted.org/freeipa/ticket/2635