[FIX] account: translate tax description in partner lang

The tax description in the taxes lines
(e.g. in invoices) is supposed
to be translated in the customer/supplier language,
as this is what is displayed in the printed reports
sent to the customer.

This is the behavior in place in Odoo 7.0 & 8.0.
(e.g. in invoices)

opw-675038

addons/account/models/account.py

@@ -666,7 +666,7 @@ class AccountTax(models.Model):
 
             taxes.append({
                 'id': tax.id,
-                'name': tax.name,
+                'name': tax.with_context(**{'lang': partner.lang} if partner else {}).name,
                 'amount': tax_amount,
                 'sequence': tax.sequence,
                 'account_id': tax.account_id.id,