Resolve "API token check true when no token is set/given"

this MR makes the architecture more fail-safe by always setting a default token on input and so it closes #258 (closed).

in addition it contains a minor change in the docker setup required for fixing an server-side issue with an "ambiguous network name": "test_default". as this is a name easily taken by a different project, i decided to include the fix immediately.

we now set an env var COMPOSE_PROJECT_NAME with an appropriate name. the standard way now would be to set a top-level name property, but this is not supported by the olde version installed server-side.

ALSO dind now includes docker-compose so our ci-docker image is obsolete and should be removed from registry and repo (Dockerfile) → #260 (closed).