[TIMOB-24335] iOS: Resolve iOS 8 deprecations

In SDK 6.0.0, we updated the default minimum iOS target to 8.0 as a result of the Xcode 8.x version that is now supported. Doing that, our iOS SDK core shows some deprecation-warnings regarding API's that should be replaced in iOS 8 and later. A selection: - Replace UISearchDisplayController with UISearchController (API migration required) - Replace NSDayCalendarUnit with NSCalendarUnitDay etc. (search and replace, easy ones) - Replace willAnimateRotationToInterfaceOrientation: (used in many places, migration required) - Replace ABPeoplePickerNavigationController (in Ti.Contacts, replacement straight forward) - Remove old statements (e.g. ![TiUtils isIOS8OrGreater]) - Remove old UIAlertView and UIActionSheet API's The first bunch of changes can be seen in [this branch](https://github.com/appcelerator/titanium_mobile/compare/master...hansemannn:TIMOB-24335?expand=1), I'm not sure when I can continue the outstanding issues, but the plan is either for 6.1.0 or 6.2.0.