[IMP] point_of_sale: add product description and product sale description to the search engine
[FIX] project: missing translations

The labels for fields 'use_tasks', 'partner_id', 'date_start' had no valid string (autogenerated or unrelated).
Make the selections of the field privacy_visibility translatable.
Fixes #3435
Merge branch '8.0' of https://github.com/odoo/odoo into 8.0-linux64