Stop using Model._deferred private attribute
Stop using Model._deferred private attribute

That attribute has been removed in Django 1.10.
See https://github.com/django/django/commit/7f51876f9

emilhdiaz/django-mptt,emilhdiaz/django-mptt,matthiask/django-mptt,emilhdiaz/django-mptt,matthiask/django-mptt,matthiask/django-mptt,emilhdiaz/django-mptt,matthiask/django-mptt