set django version to 1.8.5

requirements.txt

 dogapi==1.2.1
-django>=1.8,<1.9
+# disabled because django_extension is broken with django 1.8.6
+# https://github.com/django-extensions/django-extensions/issues/759
+# re-enable it once there is a new release availble for django-extensions 
+#django>=1.8,<1.9
+django==1.8.5
 django-extensions==1.5.5
 django-model-utils==2.3.1
 djangorestframework>=3.1,<3.2