Expose more options in docker-compose?

[JBGruber]

I'm collecting ideas what options should be exposed through docker-compose. Currently, one can set:

• location of elastic (if the user wants to run it at a different location and disable the elastic7 container)
• the port of the web client and api (default port is 80)
• the location of the data on the host machine
• some Elasticsearch option:

environment:
      - discovery.type=single-node
      - bootstrap.memory_lock=true
      - "ES_JAVA_OPTS=-Xms4g -Xmx4g"

All options for elastic work (since we're using their image), but I assume maybe some should be set by default for amcat users?