Enable App Sandbox for CC3DemoMeshUp-OSX to prevent coping kBeachBallPOD...

CC3DemoMeshUp-OSX keeps coping kBeachBallPODFile & kGlobeTextureFile to user`s documents folder.
Because the NSHomeDirectory method return user`s home directory if the app is not a sandbox app.
Turn-on the sandbox app option to prevent that (then NSHomeDirectory return app`s document folder).