v4l2 update function, video source size change, "check" unit test system integration

This part of the project on dynamic change the resolution depending on the quality of the communication channel. v4l can change resolution of the cam, so, i think this is a useful feature.
by clearing the "run" flag here, you might risk that the thread jumps out of the loop and
never starts again. it is better to do a proper thread-shutdown using pthread_join()
here, and after re-opening the device you have to start the thread again with pthread_create().