Moves all tasks run by the Celery worker into a discrete package/module
for easier installation. Also adjusts several parameters throughout to
accomplish this.
Make sure all of these move to the root of the repository first, then
return to where they were afterwards, using pushd/popd. This allows them
to be executed from anywhere in the repo.
1. Only build on GitLab when there's a tag.
2. Add the packages on GitLab to component "pvc" in the repo.
3. Add build-unstable-deb.sh script to build git-versioned packages.
4. Revamp build-and-deploy to use build-unstable-deb.sh and cut down on
output.