Under tox, install packages with --no-deps
Under tox, install packages with --no-deps

This should achieve two things:

* Make sure that we get the Django version we explicitly declare in
  tox.ini, rather than getting Django as an indirect dependency.

* Catch dependencies we forgot to declare or pin.

nimbis/django-shop,divio/django-shop,khchine5/django-shop,khchine5/django-shop,nimbis/django-shop,awesto/django-shop,divio/django-shop,jrief/django-shop,khchine5/django-shop,nimbis/django-shop,jrief/django-shop,khchine5/django-shop,awesto/django-shop,jrief/django-shop,nimbis/django-shop,divio/django-shop,awesto/django-shop,jrief/django-shop