WIP reply-to/references header in notif mail to allow reply mail

tracim/development.ini.base

 # notifications generated by a user or another one
 email.notification.from.email = noreply+{user_id}@trac.im
 email.notification.from.default_label = Tracim Notifications
+email.notification.reply_to.email = reply+{content_id}@trac.im
+email.notification.references.email = thread+{content_id}@trac.im
 email.notification.content_update.template.html = %(here)s/tracim/templates/mail/content_update_body_html.mak
 email.notification.content_update.template.text = %(here)s/tracim/templates/mail/content_update_body_text.mak
 email.notification.created_account.template.html = %(here)s/tracim/templates/mail/created_account_body_html.mak

tracim/tracim/config/app_cfg.py

         self.EMAIL_NOTIFICATION_FROM_DEFAULT_LABEL = tg.config.get(
             'email.notification.from.default_label'
         )
+        self.EMAIL_NOTIFICATION_REPLY_TO_EMAIL = tg.config.get(
+            'email.notification.reply_to.email',
+        )
+        self.EMAIL_NOTIFICATION_REFERENCES_EMAIL = tg.config.get(
+            'email.notification.references.email'
+        )
         self.EMAIL_NOTIFICATION_CONTENT_UPDATE_TEMPLATE_HTML = tg.config.get(
             'email.notification.content_update.template.html',
         )

tracim/tracim/lib/notifications.py

 from email.header import Header
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
+from email.utils import formataddr
 
 from lxml.html.diff import htmldiff
 
         for role in notifiable_roles:
             logger.info(self, 'Sending email to {}'.format(role.user.email))
             to_addr = '{name} <{email}>'.format(name=role.user.display_name, email=role.user.email)
-
+            replyto_addr = self._global_config.EMAIL_NOTIFICATION_REPLY_TO_EMAIL.replace( # nopep8
+                '{content_id}',str(content.content_id)
+            )
+            reference_addr = self._global_config.EMAIL_NOTIFICATION_REFERENCES_EMAIL.replace( #nopep8
+                '{content_id}',str(content.content_id)
+             )
             #
             #  INFO - D.A. - 2014-11-06
             # We do not use .format() here because the subject defined in the .ini file
             message['Subject'] = subject
             message['From'] = self._get_sender(user)
             message['To'] = to_addr
-
+            message['Reply-to'] = formataddr(('',replyto_addr))
+            message['References'] = formataddr(('',reference_addr))
+            # TODO: add correct header to allow reply
             body_text = self._build_email_body(self._global_config.EMAIL_NOTIFICATION_CONTENT_UPDATE_TEMPLATE_TEXT, role, content, user)