Fix side effects with csrf token, add csrf_token to every post form + add ajax (see http://stackoverflow.com/questions/5100539/django-csrf-check-failing-with-an-ajax-post-request), remove django.middleware.csrf.CsrfViewMiddleware ?!

Avoids HTTP 403 on login and reset/change password, seehttps://docs.djangoproject.com/en/dev/ref/contrib/csrf/#ref-contrib-csrf.