[IMP] sale,purchase order: order the field based on date_order instead of name

This avoids getting irrelevent order based on sequences without padding (eg: SO10 between SO1 and SO2)

bzr revid: mat@openerp.com-20140115140527-pztwh3kl6y9y7jbe

addons/purchase/purchase.py

@@ -244,7 +244,7 @@ class purchase_order(osv.osv):
     _name = "purchase.order"
     _inherit = ['mail.thread', 'ir.needaction_mixin']
     _description = "Purchase Order"
-    _order = "name desc"
+    _order = 'date_order desc, id desc'
 
     def create(self, cr, uid, vals, context=None):
         if vals.get('name','/')=='/':

addons/sale/sale.py

@@ -266,7 +266,7 @@ class sale_order(osv.osv):
     _sql_constraints = [
         ('name_uniq', 'unique(name, company_id)', 'Order Reference must be unique per Company!'),
     ]
-    _order = 'name desc'
+    _order = 'date_order desc, id desc'
 
     # Form filling
     def unlink(self, cr, uid, ids, context=None):