Add payment terms.

__init__.py

@@ -15,6 +15,7 @@ def register():
         sale.Company,
         sale.Currency,
         sale.Address,
+        sale.PaymentTerm,
         stock.Location,
         product.Product,
         product.Template,

sale.py

@@ -5,7 +5,8 @@ from trytond.model import fields
 from trytond.pool import PoolMeta, Pool
 from trytond.transaction import Transaction
 
-__all__ = ['Party', 'Company', 'Currency', 'Sale', 'SaleLine', 'Address']
+__all__ = ['Party', 'Company', 'Currency', 'Sale', 'SaleLine', 'Address',
+    'PaymentTerm']
 
 
 class Sale(ReplUUIdMasterDuplexMixin):
@@ -105,3 +106,8 @@ class Company(ReplLocalIdSrcMixin):
 class Address(ReplLocalIdSrcMixin):
     __name__ = 'party.address'
     __metaclass__ = PoolMeta
+
+
+class PaymentTerm(ReplLocalIdSrcMixin):
+    __name__ = 'account.invoice.payment_term'
+    __metaclass__ = PoolMeta