Translations for Brazilian Portuguese for account_payment_partner, accou...

...nt_payment_purchase, account_payment_sale and account_payment_sale_stock
@mileo @danimaribeiro 

In purchase module this term is translated "Ordem de Compra", this translation could be the same in purchase module... https://github.com/odoo/odoo/blob/7.0/addons/purchase/i18n/pt_BR.po#L1841