Fixes email notification that disappears silently

tracim/tracim/lib/notifications.py

 # -*- coding: utf-8 -*-
 
+from email.header import Header
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
 
         )
 
         return '{0} {1} <{2}>'.format(
-            user.display_name,
+            Header(user.display_name).encode(),
             'via Tracim',
             arranged_email,
         )