Merge pull request #1903 from thess24/master

Add back six dependency and change pbtxt files to reflect new way of …

object_detection/data/pascal_label_map.pbtxt

-item {
-  id: 0
-  name: 'none_of_the_above'
-}
-
 item {
   id: 1
   name: 'aeroplane'

object_detection/data/pet_label_map.pbtxt

-item {
-  id: 0
-  name: 'none_of_the_above'
-}
-
 item {
   id: 1
   name: 'Abyssinian'

object_detection/utils/visualization_utils.py

@@ -25,6 +25,7 @@ import PIL.Image as Image
 import PIL.ImageColor as ImageColor
 import PIL.ImageDraw as ImageDraw
 import PIL.ImageFont as ImageFont
+import six
 import tensorflow as tf