Add `healthcheck.sh` to each container

[ssoriche]

The PostgreSQL container introduced a healthcheck.sh� script that is used to determine if the container is running correctly. (this leads into Kubernetes being able to tell if a container is healthy and needs to be restarted).

The other containers need appropriate scripts to ensure they are running as well.

[ssoriche]

Work has already begun on adding healthchecks, creating a todo list to help keep track

• mongo
• postgres
• api
• web
• github-meets-cpan