mailutils: send_email() with attachments
mailutils: send_email() with attachments

* Extends mailutils.send_email() API to support attachments, following
  the recipe:
  <http://stackoverflow.com/questions/3362600/how-to-send-email-attachments-with-python>
  (closes #1253)

inveniosoftware/invenio,inveniosoftware/invenio,tiborsimko/invenio,tiborsimko/invenio