Xcode template: use iOS7 specific method for remote notifications

since we are focusing on iOS7, or more supporting iOS7 only, we should polish the push related part of the template for iOS7.

Currently we generate the following methods, if push is enabled:

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {
....    
}
 
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
.....
}

However, with iOS7 - if both are present, only the application:didReceiveRemoteNotification:fetchCompletionHandler: is invoked.

Relevant Apple documentation:
https://developer.apple.com/library/ios/documentation/uikit/reference/UIApplicationDelegate_Protocol/Reference/Reference.html#//apple_ref/doc/uid/TP40006786-CH3-SW16

The solution for this ticket is to only generate the application:didReceiveRemoteNotification:fetchCompletionHandler: method