Changes for version 6.01
- Add a post-start hook phase where we can print out custom messages or end the start phase (e.g. if rollouts are blocked).
- Pass GIT_DEPLOY_ACTION to hooks so hooks can see what action started something.
- Removed Booking.com specific Git::Deploy::Hook::* code.
- Add where to get the source to the POD and be explicit about what license git-deploy is under.
- Fixed an issue where we'd die when trying to print out an error on invalid refs.
- Add facility to emit custom error messages on sync hook failure by setting deploy.message-on-sync-hook-fail-whale in the config.
- Skip tests (instead of failing) on platforms that don't have Git installed.