Releasing ShopifyAPI

1. Check the Semantic Versioning page for info on how to version the new release: http://semver.org
2. Update the version of ShopifyAPI in lib/shopify_api/version.rb
3. Add a CHANGELOG entry for the new release
4. Commit the changes with a commit message like "Packaging for release X.Y.Z"
5. Tag the release with the version (Leave REV blank for HEAD or provide a SHA)
  $ git tag vX.Y.Z REV
6. Push out the changes
  $ git push
7. Push out the tags
  $ git push --tags
8. Publish the gem using Shipit
9. Consider if the dependency in Shopify/shopify needs updated. It's used only by the tests so is a low risk change.
Also consider Shopify/shopify_app whose gemspec depends on this.
We don't need to do this for every release, but we should try to keep them relatively up to date.