ci: review apps may use container volumes

This is added to allow some (or all) environments to deploy containers with volumes accessible from the host system. In this instance, it's desireable to deploy the staging environment using gunicorn which is what's going to be used in production.

However unlike the Django development server, gunicorn requires the proxy service (Apache2) to be configured to serve static files directly from the filesystem. Provisioning a volume and setting BASE_DIR will make this possible.