Add Django requirements file to devstack req list.

playbooks/roles/edxapp/vars/devstack.yml

@@ -11,6 +11,7 @@ edxapp_requirements_files:
   - "{{ custom_requirements_file }}"
   - "{{ local_requirements_file }}"
   - "{{ base_requirements_file }}"
+  - "{{ django_requirements_file }}"
   - "{{ post_requirements_file }}"
   - "{{ paver_requirements_file }}"
   - "{{ development_requirements_file }}"