Replace background separation with per-pixel segmentation

[batchku]

Kitani's Per-pixel segmentation:
http://www.cs.cmu.edu/~kkitani/perpix/code_perpix/

Training data for above algorithm:
http://www.cs.cmu.edu/~kkitani/datasets/

Labeling tool for making our own training data:
http://www.cs.cmu.edu/~kkitani/perpix/code_grabcut/