Create test docker-compose.yml to simplify running router by end-users

[sfoxdev]

[rhlsthrm]

We received some feedback from our users that they would like to not use the config file and instead use env vars directly: https://github.com/connext/vector/pull/381

We should look into some sort of config management/abstraction tooling. A suggestion for how things should look and work: https://docs.teku.consensys.net/en/latest/Reference/CLI/CLI-Syntax/