Fix #31 streamline CHANGELOG
Fix #31 streamline CHANGELOG

- explicitly define categories (IMPROVEMENTS, BUG FIXES, OTHER)
- enhancements are Type: Enhancement, Type: Feature Request
- refactor title to use GITHUB_REPO
- adjust whitelist include_labels to CHANGELOG
- eliminate blacklist exclude_labels

4-20ma/I2cDiscreteIoExpander,4-20ma/I2cDiscreteIoExpander