release management

1. Use github compare view to generate a list of changes since the commit of the last release, i.e. https://github.com/mendicant-university/newman/compare/v0.2.0...v0.2.1#diff-43

2. Do a comprehensive audit of documentation to make sure that any changes introduced were documented properly, and no content is out of date. Also check README for outdated or incomplete documentation.

3. Update the CHANGELOG.md file with descriptions of changes / improvements

4. Update lib/newman/version.rb if necessary

5. Create and push a tag for the release, i.e. v0.2.1

6. Build a new gem, test it manually, then push to rubygems.org

7. Check these release management notes to see if any important details are missing, and update if necessary.