ImageDisplayerOCV

Hello, @nitishsrivastava 

I implemented first version of ImageDisplayer using OpenCV and removed CImg dependency. However I tried not to break anything, but I didn't fully understand some code, for example, line:
 val = data[image_id + num_images * (j + width_ * (i + k * height_))];
with confusing variables' names: image_id & num_images. First looks like absolute offset to the image and for the second one I always used 1 in testing code.