Use Tabs
Hopefully clearer help for --skip-current
Hopefully clearer help for --configuration
Clean up code branch for --no-key vs. --key
Revert "Clean up code branch for --no-key vs. --key"

This reverts commit 73f6c1bf0e9a19e01afd117d62024b863e38eae6.
Use a ternary for defaultValue
Merge pull request #117 from Carthage/command-improvements

Improve Command implementation and user-visible help
Merge remote-tracking branch 'origin/master' into carthage-managed-submodules