Add Chinese Simplified Translation

[greenflute]

Hi, just added Chinese Simplified Translation, most Xibs sind intact, except the AboutWindow.xib.

Since i haven't managed to bypass the System-Extension check (although with my own apple development certs everything compiles), i can only check most xibs (except the welcome splash) under Xcode Interface Builder.

There are still some strings which were not translated, e.g "must run from /Application", and some rule type tips in "Add Rules" Xib. I think it needs some refactoring in AppDelegate, WelcomeWindowController and RulesWindowController.

Thanks for this great tool, hope i can somehow contribute to it.

[LanYunDev]

I think it's a worthwhile thing to do!