Releasing shopify_python_api

1. Verify that the examples in the README are still valid against the latest stable API release.

2. Check the Semantic Versioning page for info on how to version the new release: http://semver.org

3. Update version in shopify/version.py

4. Update CHANGELOG entry for the release.

5. Commit the changes
    git commit -m "Release vX.Y.Z"

6. Tag the release with the version
    git tag -m "Release X.Y.Z" vX.Y.Z

7. Push the changes to github
    git push --tags origin master

8. Shipit!