fix RequestContext deprecation warnings
fix RequestContext deprecation warnings

epantry/django-sql-explorer,groveco/django-sql-explorer,enstrategic/django-sql-explorer,dsanders11/django-sql-explorer,groveco/django-sql-explorer,enstrategic/django-sql-explorer,groveco/django-sql-explorer,enstrategic/django-sql-explorer,dsanders11/django-sql-explorer,enstrategic/django-sql-explorer,dsanders11/django-sql-explorer,epantry/django-sql-explorer,dsanders11/django-sql-explorer,epantry/django-sql-explorer,groveco/django-sql-explorer