Changes in order to make it work with GCP
- IS_GCP added. When True, CLIENT_ID is not used in topics.
- Dynamic JWT creation is created.
- If IS_GCP is True, MQTT_PASSWORD should be the private_key pem file.
- JWT_ALG specifies the signing algorithm.
- JWT_EXP_IN_MINUTES specifies the experition time of jwt.
- docker-compose.yml added for easier deployment.
- Dockerfile changed for convinience.