Build separate various binary tarballs

Also a bunch of script clean up.  Make make-clean.sh faster and more robust.

Building the docker run images and uploading to GCS are now optional and turned off by default. Doing a release shouldn't hit the network now (I think).
Nit: /bin is a target directory, so I'd advise adding a trailing slash.

It took me quite a while to understand the variable substitution (cool trick btw!) so you might want to add a comment that that list will expand to the binaries including the prefix of ${LOCAL_OUTPUT_ROOT}/build/${platform}/