Update some API references that had fallen out of use.
Notably this no longer ran, since docker.#Run now asks for an "input" not an "image," alpine.#Image became alpine.#Build and you have to reference its output.
Remove a FIXME -- now copies the inline script to the container as a file rather than executing it with python -c.
Add tests
Signed-off-by: Adam Smith <adamsmith@nottheeconomist.com>