adding dependency on grabcut_3d; pulling the current bb->mask code into function
First pass at having the segmentation pipeline actually include grabcut output.

ToDo:
* Better display of mask data in im_gui (currently, it's rgb vs. random noise)
* Implement actual pixel labeling in the im_gui (right now, it just displays
the mask and waits for the user to click "accept")
* Implement iterating on human input in ben_segmentation
whoops. Forgot to add this file on previous commit
...and this one
Merge branch 'master' of https://github.com/lindzey/shared_autonomy_perception