upgrade to dc v3 and add depends_on

Author: James Lee

docker-compose.yml

@@ -1,11 +1,12 @@
-version: '2'
+version: '3'
 services:
   dockerapp:
     build: .
     ports:
       - "5000:5000"
     volumes:
       - ./app:/app
-
+    depends_on:
+      - redis
   redis:
     image: redis:3.2.0