change django install_requires version (#101)

Fix the django install)requires version in setup.py so that it allows versions of django 1.11.x

setup.py

@@ -68,7 +68,7 @@ def get_package_data(package):
       include_package_data=True,
       packages=get_packages('defender'),
       package_data=get_package_data('defender'),
-      install_requires=['Django>=1.8,<=1.11', 'redis>=2.10.3,<3.0',
+      install_requires=['Django>=1.8,<1.12', 'redis>=2.10.3,<3.0',
                         'hiredis>=0.2.0,<1.0', 'mockredispy>=2.9.0.11,<3.0'],
       tests_require=['mock', 'mockredispy', 'coverage', 'celery', 'django-redis-cache'],
       )