Invoke-release

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- Added requirements and documentation.

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- Back-added old changelog message.
- Improved changelog output format.

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- Created new reusable command-line release tool for Eventbrite libraries and services.
- Improved language, spelling, and grammar on output messages.
- Added support for additional exit points and multi-line changelog messages.
- Fixed bugs from version 0.1.0.

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- Initial test release.