replaced block grasp with moveit grasp server

This repo is very helpful, but the instructions in your repository don't seem to work as provided. The block_grasp_generator is never launched, as far as I can tell. 

Simply replacing the block generator with the corresponding moveit_simple_grasp action and remapping the topics appropriately on the command line seems to make it work. 

rosrun moveit_grasping_testing pick_and_place.py /grasp_generator_server/generate:=/moveit_simple_grasps_server/generate

You may want to either update the launch files or accept these changes.