prepared app for production (removed global variables, add flask-pymongo as db driver

src/backend_flask/Makefile

@@ -0,0 +1,16 @@
+IMG="backend-flask"
+CNT="backend_flask"
+
+clean:
+	- docker rm -f $(CNT)
+
+run: clean build
+	docker run -d --net host --name $(CNT) $(IMG)
+	docker logs -f $(CNT)
+
+build: build-cjvt-python-env
+	# docker build . -f ../../Dockerfile-backend-flask -t $(IMG)
+	cd ../..; docker build . -f Dockerfile-backend-flask -t $(IMG)
+
+build-cjvt-python-env:
+	cd ../../dockerfiles/python-env; $(MAKE) build