[IMP] survey: trace partners who are logged in

- Task: https://www.odoo.com/web?#id=9147&view_type=form&model=project.task&action=333&active_id=131
- Pad: https://pad.odoo.com/p/openerp-project.task-JT0U0WBHU3
Done!
Remove request.session.uid.