Make individual components delegate private

The `delegate` property should only be set on `[BITHockeyManager sharedHockeyManager]` which will then propagade it to all components. Setting the delegate individually per component could cause undefined behaviour.

Classes/BITAuthenticator_Private.h

@@ -34,6 +34,18 @@
 
 @interface BITAuthenticator ()<BITAuthenticationViewControllerDelegate, UIAlertViewDelegate>
 
+/**
+ Delegate that can be used to do any last minute configurations on the
+ presented viewController.
+ 
+ The delegate is automatically set by using `[BITHockeyManager setDelegate:]`. You
+ should not need to set this delegate individually.
+ 
+ @see `[BITHockeyManager setDelegate:]`
+ @see BITAuthenticatorDelegate
+ */
+@property (nonatomic, weak) id<BITAuthenticatorDelegate> delegate;
+
 /**
  * must be set
  */