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The NSDateFormatter is coded into the compiled binaries for each application. They may grab formats from other .plists or .strings but that is going to be harder to find and it is up to the developer. NSDateFormatter is only available when writing the code.
Since each application stores these in their own way, you will have to look through their language files. This is up to the developer. Skype.app is merely an example.
I would stay away from the Hackintosh stuff, @houbysoft is right, its more trouble then it is worth. If your goal is to be a developer with a gaming rig then the last thing you want to worry about is your OS tripping up on hardware or vise-versa.
If your really worried about the source control, just use a thirdparty app like Tower for git or CornerStone for SVN. Better yet, learn the command line interface.