Use cpack to create osx's dmg

Additionally, ensure proper installation of sounds and zonebg resources.
This by now is needed in order to create a working OSX package, but can be a base to create linux packages (deb/rpm) or a nsis script for windows in the future.
The setting string. I need a way to understand if the user already set those options in the past to avoid overwriting them. Only if all of them are empty, i assume the user didn't ever touch those settings, so i'm fine creating a default value for him.
Then, i also check if the "zonebg" directory already exists; if it exists, i won't touch the settings, because i suppose the user already saw the default settings and removed them.