Multiple binaries can be specified, but only the latest is installed

[leucos]

Example for docker-slim.

This spec installs both binaries but docker-slim-sensor will be installed at ~/.binenv/binaries/docker-slim/X.Y.Z.

    install:
      type: tgz
      binaries:
        - docker-slim
        - docker-slim-sensor

Another argument (see #171) to change binaries layout from binaries/DIST/VERSION to binaries/DIST/VERSION/BINARYNAME