[fix] add support to django 1.9
[fix] add support to django 1.9

johtso/django-smart-selects,johtso/django-smart-selects,PetrDlouhy/django-smart-selects,knixeur/django-smart-selects,savoirfairelinux/django-smart-selects,digi604/django-smart-selects,knixeur/django-smart-selects,savoirfairelinux/django-smart-selects,digi604/django-smart-selects,PetrDlouhy/django-smart-selects