Grouped actions into single run commands - saves a bit of space

Ah ok I see what you are trying to do. But each line ie a RUN or ADD command in the Dockerfile is done in a new container and then committed to the image during a build. So having that clean up line at the end of the dockerfile actually doesn't remove anything from the final image, it just removes it from the final layer. For example a simple dockerfile that contains:

ADD 100mb_test.file /usr/local
ADD 100mb_test2.file /usr/local
RUN rm -rf /usr/local/100mb_test*

will still result in an image that is 200mb, even though if you enter the container and look in /usr/local there will be nothing there. Thats why I suggested grouping the items together in a single run command and putting the clean up tasks at the end of the single RUN command to reduce the amount of layers and cruft that gets saved into the final image.
Theres a bit more info here if you like http://jonathan.bergknoff.com/journal/building-good-docker-images
and there is an open issue here for Docker requesting the ability to flatten docker images after build
https://github.com/docker/docker/issues/332

Totally understand the desire to devote time to developing Sal rather than the packaging/delivery solution.

If its ok with you I'll just fork it and then tweak it to meet my needs