Remove more Django 1.6 and 1.7 tox config that was missed.

Author: mblayman

tox.ini

@@ -15,8 +15,7 @@ deps =
        drf3.1: djangorestframework==3.1.3  # Should track maximum supported
        drf3.2: djangorestframework==3.2.2  # Should track maximum supported
        drf3.3: djangorestframework==3.3.2  # Should track maximum supported
-       py27-django1.6-drf{2.4,3.0,3.1,3.2,3.3}: -rrequirements/optionals.txt
-       py27-django{1.6,1.7,1.8,1.9}-drf{3.1,3.2,3.3}: djangorestframework-oauth==1.0.1
+       py27-django{1.8,1.9}-drf{3.1,3.2,3.3}: djangorestframework-oauth==1.0.1
        -rrequirements/testing.txt
 
 [testenv:py27-flake8]