Improvements

* Add Xcode 8 support: rename "OS X" to "macOS" (#5385)
* Add support for relative file paths to `copy_artifacts` action (#5354)
* Add force option to `add_git_tag` action (#5348)
* Improve error messages for `black_list` for invalid lane names or when name it taken
* Update `xcode-install` version to 2.0.0 (#5322)

https://github.com/fastlane/fastlane/releases/tag/1.98.0
