Addded AV (Camera and Microphone) Permissions check

Added the changes that @tromg suggested, modifying them to support both Camera and Microphone.  I also added all the method headers to the private interface.  There is both a generic `showAVPermissionsWithType:` method as well as `showCameraPermissionsWithTitle:` and `showMicrophonePermissionsWithTitle:` methods.