test_vgg16_placeholder.py is having some issues and not running correctly

[jlinsley1983]

Nick is still unable to get it to run, getting this error: "ValueError: Cannot feed value of shape (16, 224, 224, 3) for Tensor u'images:0', which has shape '(?, 224, 224, 1)'"

[drewlinsley]

Added some error handling to the script. I think this could be because config.model_image_size is set to something like height/width/1 but the script is expecting that to be height/width/3.