This commit allows the creation of distributions, with 0.0.1 being the first version.
See distro/README.md for details on how to build a release.
This commit also uses a new version of the Bazel federation that contains rules_pkg 0.2.2 instead of 0.2.1.
There are still some problems with the WORKSPACE stanza that is being printed by the release notes generation script, though:
- It references a //cc:deps.bzl file, which doesn't exist. I have to modify the scripts in rules_pkg to support a flag like 'has_deps'.
- It doesn't support the Bazel federation yet, since it always tells users to download code from the rules_cc repository.
