Adding PR2-specific launch files, as required by this project

* pr2_hydro.launch is from /etc/ros/hydro/robot.launch, modified to point to robot_hydro.launch
* robot_hydro.launch is from /opt/ros/hydro/share/pr2_bringup/pr2.launch, modified to:
  * remove arm & head cameras
  * start up the head-mount kinect
  * remove the EKF, replace with static_transform_publisher from odom_combined -> base_footprint (to avoid the tiny angular offsets in pose)
starting work on a single launch file and state machine that can handle any combination of our pick & place pipeline's options
unified clear-table script now exists:

* clear_table_unified.launch can now switch between ORK/Grabcut object segmentation,
based on command-line argument
* this required combining clear_table_moveit.py and clear_table_moveit_ork.py
* assumes that robot.launch, rviz, move_group, and ork_core are launched separately
removing buffer below object (bad idea), fixing add table code (bugs added yesterday when I made pose/dims optional)
code that tries Ioan's suggestion of sending the entire environment update at once. I'm not sure it's an improvement...
merging after cherry-pick had conflicts
adding stuff to the clear_table script to try to debug moveit; launchfile now launches rosbridge
changing click radius to make more sense for the JS interface
Update pr2_hydro.launch
Update robot_hydro.launch
Update openni_segmentation.launch
Merge pull request #19 from SharedAutonomyToolkit/launch-files

Launch files