streamlined for latest ruby verson on rpi build
streamlined for latest ruby verson on rpi build

openwebcraft/rpi-dashing,openwebcraft/rpi-docker-dashing,openwebcraft/rpi-docker-dashing,openwebcraft/rpi-dashing,openwebcraft/rpi-docker-dashing,openwebcraft/rpi-docker-dashing,openwebcraft/rpi-dashing,openwebcraft/rpi-dashing