Add persistent Redis data store and copy over Druid config to production

docker/docker-compose.prod.yml

@@ -324,6 +324,7 @@ services:
          hard: 65535
     volumes:
       - ${PORTAINER_GIT_DIR}/docker/redis.conf:/etc/redis.conf
+      - redis_data:/data
     volumes_from:
       - tmp
     healthcheck:
@@ -338,6 +339,7 @@ networks:
          name: pathogen
 
 volumes:
+  redis_data: {}
   superset_home:
     external: false
   db_home: