Pascal VOC directory fix

[ahundt]

The pascal voc directories need to be fixed as they are currently in multiple locations, leading to confusion.

This file: https://github.com/warmspringwinds/tf-image-segmentation/blob/master/tf_image_segmentation/utils/pascal_voc.py

should most likely be in this folder: https://github.com/warmspringwinds/tf-image-segmentation/tree/master/tf_image_segmentation/recipes/pascal_voc

Either that or vice-versa...

I can make the change just need to confirm the best option.