Add update-all.sh script to rebuild only out of date packages

Something like this is necessary in order for the cookbook to replace the Makefiles in the redox repo.

Although I guess for the build in the redox repo, you want to build only some packages (those that are part of the base system).

Fucking awesome. I will merge asap and use on static.redox-os.org

I've thought of a potential issue. If a build fails, but a package is present from a previous build of a previous version, it will assume that the package is up to date.

The correct solution is to store version metadata in the package tar. The easy solution is to just remove the stage.tar before trying to build.

sounds good. I have made changes to use fetch instead of update, as it is more correct. Also added publishing of packages at the end.