djangorestframework >= 3.7 dropped support for Django<1.10

See http://www.django-rest-framework.org/topics/release-notes/#370

Therefore CI-tests fail.

There are 2 Options: a) Require djangorestframework<3.7 b) Drop support for Django<1.10

Note that the only version of Django<1.10 still supported is Django-1.8. And the extended support for 1.8 ends in April.