[FIX] mail: auto_delete option on email notification

When writing a message via the chatter with a template being in auto_delete
False, the notifications emails are always in auto_delete True.

This fix propagate the auto_delete option of a mail.template to these
notifications emails.

opw-630010

addons/mail/mail_followers.py

@@ -213,7 +213,7 @@ class mail_notification(osv.Model):
         for chunk in chunks:
             mail_values = {
                 'mail_message_id': message.id,
-                'auto_delete': True,
+                'auto_delete': (context or {}).get('mail_auto_delete', True),
                 'body_html': body_html,
                 'recipient_ids': [(4, id) for id in chunk],
                 'references': references,