Launch additional services in separate container #119

The additional services (like Postgres or RabbitMQ) should be started as additional Docker services. This could for example be achieved via docker-compose.

AiiDAlab-launch would likely need some major revision to then support this, since it currently uses docker directly to manage the container(s).

Sub-tasks:

• Create proof-of-concept docker-compose file that demonstrates the approach
• Evaluate how we want to manage multiple containers within the context of aiidalab-launch (docker-compose, manually, external tool ?)
• Revise aiidalab-launch to manage multiple containers based on approach identified in previous step

Dependencies

• Base AiiDAlab image on jupyter/base-notebook image and support AiiDA 2.0 aiidalab-docker-stack#254