Release procedure

Make sure you are in the master branch, with the latest changes, and a clean copy
```
git checkout master
git pull
git status
```

Decide a new version number (with major, minor, patch components) and apply it in all packages' setup.py

VERSION_MAJOR=X
VERSION_MINOR=Y
VERSION_PATCH=Z
VERSION=$VERSION_MAJOR.$VERSION_MINOR.$VERSION_PATCH
SETUP_FILES="daliuge-common/setup.py daliuge-translator/setup.py daliuge-engine/setup.py"
echo $SETUP_FILES | xargs sed -i "s/MAJOR = .*/MAJOR = $VERSION_MAJOR/; s/MINOR = .*/MINOR = $VERSION_MINOR/; s/PATCH = .*/PATCH = $VERSION_PATCH/"

Double-check these are the only changes you will commit
```
git diff
```

Commit the version changes

git commit $SETUP_FILES -m "daliuge $VERSION"

Tag the repository with a new version name tag (using vX.Y.Z format)

git tag v$VERSION -m "daliuge $VERSION"
# Alternatively, if you want to sign it
git tag v$VERSION -m "daliuge $VERSION" -s

Push the new commit and the tag to GitHub
```
git push origin master v$VERSION
```

Produce and collect source distributions for all packages

python setup.py sdist
for package in daliuge-common daliuge-translator daliuge-engine; do
  cd $package
  python setup.py sdist
  cp dist/*-$VERSION.tar.gz $OLDPWD/dist
  cd $OLDPWD
done

Upload to PyPI

pip install twine
# Adjust credentials in ~/.pypirc, then
twine upload dist/daliuge*-$VERSION.tar.gz