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

blaklites/django-rest-framework-jwt,orf/django-rest-framework-jwt,shanemgrey/django-rest-framework-jwt,ArabellaTech/django-rest-framework-jwt,GetBlimp/django-rest-framework-jwt,plentific/django-rest-framework-jwt