[BUG FIX] Fix for Issue #19. Fixes crashes on iOS 5.0, where calls to NS...

[ruohoruotsi]

..._AVAILABLE_IOS(6_0) methods were not protected by instancesRespondToSelector checks. #19

[HBehrens]

Thanks, Ruoho. Did you check how this impacts the theming on iOS5?

[ruohoruotsi]

Hi Heiko,
This does not affect themes/theming, as these calls are iOS6 only. This code only prevents invocation of such calls to an API (iOS6) newer than the minimum deployment target (iOS5).

I followed the directions here:
https://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/cross_development/Using/using.html

I currently have an iPad 1 running 5.1.1. I saw this issue immediately because these calls are not supported on iOS5 (which is currently the minimum deployment target). This is a non-issue for any iOS6 system. I hope this helps. Let me know if you need any more information or concerns about this commit.

cheers,
RR