cosmetic changes to ben_segmentation.cpp; adding COMPONENTS to its CMakeLists.txt
changing BoundingBox action; adding script for im_hmi that just returns the central half of the image
fixing CMakeLists to add dependency on shared_autonomy_msgs s.t. parallel builds are OK
adding notes to myself to CMakeLists about when to use diff options
ben_segmentation now calls to the im_hmi server to obtain a bounding box