Allow users to disable quoting completely or use a different quote string

Allow users to disable quoting completely or use a different quote string.

This is needed to fix `grunt-contrib-sass` as the current issue there is only solvable by removing quoting completely. Otherwise it will fail under Linux and OSX.
Yep, it may be so. See https://github.com/sindresorhus/dargs/issues/11#issuecomment-53614324.