Improve docker compose performance (#347) 🤩

* Fix warning Integrity check: System parameters don't match

* Reduce commands required to use docker-compose and update quick-setup doc

Data will still persist when stopping and restarting containers.
To destroy the data can use docker-compose down --volumes

* Moved webpacker-dev-server to its own service

* cache bundle and yarn - improve volume performance - env conditional statements

* Fix inconsistent build results found during testing

docker/entrypoint.sh

@@ -5,4 +5,4 @@ set -e
 rm -f /app/tmp/pids/server.pid
 
 # Then exec the container's main process (what's set as CMD in the Dockerfile).
-exec "$@"
+exec "$@"