Add python 3 support

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__ = 'galatea.configuration'
     tutorial_thumb_size = fields.Integer('Tutorial Thumb Size',
         help='Thumbnail Tutorial Image Size (width x height)')

galatea.py

@@ -6,10 +6,10 @@ from trytond.model import fields
 from trytond.pyson import Eval
 
 __all__ = ['GalateaWebSite']
-__metaclass__ = PoolMeta
 
 
 class GalateaWebSite:
+    __metaclass__ = PoolMeta
     __name__ = "galatea.website"
     tutorial_comment = fields.Boolean('Tutorial Comments',
         help='Active tutorial comments.')