Added option to .xacro file, "hide_underactuated", to hide the outside
"fingers" of the Robotiq gripper. Added back in the transmissions for
the fingers to the robotiq URDF file, so that they show up correctly in
RVIZ and so that MoveIt can plan. MoveIt cannot find valid positions for
the gripper, so currently the gripper is disabled in
ur5_robotiq_joint_limited.urdf.xacro.