Ios8

This branch will prevent possible crashes and discontinue use of deprecated methods in iOS 8. Important changes of note are:
- UIAlertView is switched to UIAlertController if possible. Relevant for surveys.
- Use of interfaceOrientation in determining MPMiniNotification framing is unnecessary in iOS8 and is removed.
- Registration for push notifications in the example app has been updated to use newer methods. 
Do you know the pros and cons of using this vs using `__IPHONE_OS_VERSION_MAX_ALLOWED >= 80000` ? I'm unclear on why one might be better than another, but I think we should def be consistent. Apple seems to suggest the [max_allowed way](https://developer.apple.com/library/ios/documentation/DeveloperTools/Conceptual/cross_development/Using/using.html#//apple_ref/doc/uid/20002000-1114741-CJADDEIB)