Djmail

- Pass extra kwargs to EmailMultiAlternatives in MagicMailBuilder.
Thanks to ad-m.
- Premailer: Fix call when html is None and create a mixin to be more reusable.
Thanks to davidfischer-ch.
- Declare any non-HTML body as text/plain (e.g. JSON).
Thanks to davidfischer-ch.
- Fix issue 22: Celery backend: Handle other serializers than pickle (JSON, yaml...)
Thanks to davidfischer-ch.

- Translate email subject.
- Now the project will be maintened by David Barragan (bameda).

- Drop compatibility with django 1.4
- Refactored email rendering making it more efficient using translation switching.
- Better handling different type of emails (html-only, text-only and both).

- code cleaning (pep8) (by davidfischer-ch)
- fix wrong parameters on management command (by mathieuhinderyckx)

- Fixed errors' handling in python2.

- Add missing modules not included in the previous version.
- Django 1.4.x support added.
- Minor code cleaning.