[StatusBar] Fix iOS8 Deprecation Warnings

Issue has been around for a while
https://github.com/apache/cordova-plugin-statusbar/pull/26

After use Cordova build ios
there are some warning about UIDeviceOrientation and UIInterfaceOrientation:
Implicit conversion from enumeration type "UIDeviceOrientation"(aka "enum UIDeviceOrientation") to different enumeration type "UIInterfaceOrientation" (aka "enum UIInterfaceOrientation")

Based on current ios api, UIViewControl.interfaceOrientation has been deprecated.

Fixed those warning using function: [[UIDevice currentDevice] orientation] instead of self.viewController.interfaceOrientation