Update to Django >=2.0.8

Fixes CVE-2018-14574: Open redirect possibility in CommonMiddleware

requirements.txt

-Django>=2.0.3,<2.1
+Django>=2.0.8,<2.1
 django-localflavor>=2.0,<2.1
 Pillow>=5.0,<5.1
 django-compressor>=2.1,<3