Fix keyboard for native targets.

I've tested targets cpp/neko/flash/html5 on linux with 2 azerty keyboards, all keys defined in utils.Key.hx are working.

I've also tested on windows neko/flash, beside the fact that neko believed my keyboard was a qwerty (it's an azerty) all worked fine.

See issue https://github.com/HaxePunk/HaxePunk/issues/71

Needs to be tested with a qwerty keyboard, and if possibly another layout, to see if that's a universal fix or not.