1) Fixed deadlock if camera is started and stopped immediately
2) Invalid pattern usage of Object.wait(). Refer to "spurious wakeup": http://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait
3) Fixed buffer usage:
  a) fix eliminates processing of zero NV12 (green in RGB) first frame
  b) latest ready frame is delivered for processing (not previous)

- previous pull request: https://github.com/Itseez/opencv/pull/3340

rename cv::cuda::internal namespace
to cv::cuda::device to prevent conflicts
with cv::internal