[FIX] account: make invoice report reprint from attachment again

A few month ago, based on unclear specs, something was merged.
Today, we come back, since it does not do what we want. We do
not take into account the fact that between 2 printings, the user
has changed its report layout or its data company.

Initial commit : dccfdb0ddb

addons/account/views/account_report.xml

@@ -9,6 +9,7 @@
             report_type="qweb-pdf"
             name="account.report_invoice"
             file="account.report_invoice"
+            attachment_use="True"
             attachment="(object.state in ('open','paid')) and ('INV'+(object.number or '').replace('/','')+'.pdf')"
         />