Use declarative index definition for ModelSQL

issue5757
review361251002

party.py

@@ -48,7 +48,7 @@ class PartySalePriceList(ModelSQL, CompanyValueMixin):
     "Party Sale Price List"
     __name__ = 'party.party.sale_price_list'
     party = fields.Many2One(
-        'party.party', "Party", ondelete='CASCADE', select=True,
+        'party.party', "Party", ondelete='CASCADE',
         context={
             'company': Eval('company', -1),
             },