[FIX] portal_sale: portals are not allowed to see payments

Portal users are not allowed to read account.move.line model
Therefore, in the portal, if you let the payments in the invoice view, the portal user is warned that he is not allowed to see account.move.line
[IMP] Increase statics cache from 12 hours to 1 week
Merge branch '8.0' of https://github.com/odoo/odoo into 8.0-linux64