Release scripts: Update create-tarball to include docs and other packaging details.

Release scripts: Update create-tarball to include docs and other packaging details.

I've updated the create-tarball script to support command line options,
docs build (or copy and existing build), and to run the packaging update
scripts.

  $ release-scripts/create-tarball --help
  Usage release-scripts/create-tarball [options]
      --help             Print command usage
      --branch <name>    Specify the branch to to create the archive file from
      --copy-docs <dir>  Copy documentation from <dir> rather than building
      --tag <name>       Tag name for release
      --keyid <email>    The GnuPG key ID used to sign the release tag
(This used to be commit 7c96795e5954b6a716beb6f5a30d6c7bb1647717)