[IMP] Onboarding tip: fixes (access rights, list view support) + model migration to v8 style

 - Task: https://www.odoo.com/web#id=8829&view_type=form&model=project.task&action=333&active_id=248
 - Pad: https://pad.odoo.com/p/r.oApOBCOkXPXIgxCW
That does one request for each record, any reason to not use `@api.multi`? Should make no difference to the code itself...