Remove gripper_controllers dependency (#1045)

Author: fmauch

package.xml

@@ -47,7 +47,6 @@
   <!-- <exec_depend>franka_description</exec_depend> -->
   <!-- <exec_depend>moveit_commander</exec_depend> -->
   <exec_depend>controller_manager</exec_depend>
-  <exec_depend>gripper_controllers</exec_depend>
   <exec_depend>joint_state_broadcaster</exec_depend>
   <exec_depend>joint_state_publisher</exec_depend>
   <exec_depend>joint_trajectory_controller</exec_depend>