Update simple_videofacerec.py

xrange(max(labels)) would start count at 1, were as we want it to start at 0. So that len(list_of_labels) == len(subject_names)

If the subject detected was the last folder used for training, we hit an Key Error, on self.model.subject_name[prediction].
Merge pull request #17 from DrinkingGypsie/patch-1

Update simple_videofacerec.py