feat(docker-compose): add config to _use_ the toolchain image locally
feat(docker-compose): add config to _use_ the toolchain image locally

Introduce `docker-compose.yml` to build and run the `toolchain` ("dcos-ui")  docker image locally using `docker-compose`. The `toolchain` container features all tools needed to run the development environment as well as the integration and system tests.

dcos/dcos-ui,dcos/dcos-ui,dcos/dcos-ui,dcos/dcos-ui,dcos/dcos-ui