We need to verify and create tests for Mac installer specific signing options:
--mac-sign
      Request that the bundle be signed.
--mac-bundle-signing-prefix <prefix string>
      When signing the application bundle, this value is prefixed to all components
      that need to be signed that don't have an existing bundle identifier.
--mac-signing-key-user-name <user name>
      User name portion of the typical "Mac Developer ID Application: " signing key.
--mac-signing-keychain <file path>
      Location of the keychain to use. If not specified, the standard keychains are used.