chore(requirements): update djangorestframework to 3.6.2

See http://www.django-rest-framework.org/topics/3.6-announcement/#django-rest-framework-36

Author: mboersma

rootfs/requirements.txt

@@ -4,7 +4,7 @@ Django==1.10.6
 django-auth-ldap==1.2.10
 django-cors-middleware==1.3.1
 django-guardian==1.4.6
-djangorestframework==3.5.4
+djangorestframework==3.6.2
 docker-py==1.10.6
 gunicorn==19.7.0
 idna==2.5