Add python 3 support

address.py

@@ -5,10 +5,10 @@ from trytond.model import fields
 from trytond.pool import Pool, PoolMeta
 
 __all__ = ['Address']
-__metaclass__ = PoolMeta
 
 
 class Address:
+    __metaclass__ = PoolMeta
     __name__ = 'party.address'
 
     @staticmethod

configuration.py

@@ -5,10 +5,10 @@ from trytond.model import fields
 from trytond.pool import PoolMeta
 
 __all__ = ['Configuration']
-__metaclass__ = PoolMeta
 
 
 class Configuration:
+    __metaclass__ = PoolMeta
     __name__ = 'party.configuration'
     default_country = fields.Property(fields.Many2One('country.country',
             'Default Country'))