Use standard-version to automate release tasks

[abmusse]

standard-version does the following:

1. bumps the version in metadata files (package.json, composer.json, etc).
2. uses conventional-changelog to update CHANGELOG.md
3. commits package.json (et al.) and CHANGELOG.md
4. tags a new release

Our commits would need to follow the Conventional Commits Spec.

Following these conventions would allow us to auto generate CHANGELOG.md based on our commits.