[imp] mail: display who likes a post

 - Task: https://www.odoo.com/web#id=8679&view_type=form&model=project.task&action=333&active_id=131
 - Pad: https://pad.odoo.com/p/r.VlbOhsbzhWbR4Cga
Please replace the "more" link with a "and x users more" where x is data.length - limit (if x > 0)