Decouple swappable joints from stop/runstop services

stretch_core/nodes/stretch_driver

@@ -277,11 +277,10 @@ class StretchBodyNode:
             self.robot.lift.move_by(0.0)
             self.robot.push_command()
 
-            self.robot.head.move_by('head_pan', 0.0)
-            self.robot.head.move_by('head_tilt', 0.0)
-            self.robot.end_of_arm.move_by('wrist_yaw', 0.0)
-            self.robot.end_of_arm.move_by('stretch_gripper', 0.0)
-            self.robot.push_command()
+            for joint in self.robot.head.joints:
+                self.robot.head.move_by(joint, 0.0)
+            for joint in self.robot.end_of_arm.joints:
+                self.robot.end_of_arm.move_by(joint, 0.0)
 
         rospy.loginfo('Received stop_the_robot service call, so commanded all actuators to stop.')
         return TriggerResponse(
@@ -321,11 +320,10 @@ class StretchBodyNode:
                 self.robot.lift.move_by(0.0)
                 self.robot.push_command()
 
-                self.robot.head.move_by('head_pan', 0.0)
-                self.robot.head.move_by('head_tilt', 0.0)
-                self.robot.end_of_arm.move_by('wrist_yaw', 0.0)
-                self.robot.end_of_arm.move_by('stretch_gripper', 0.0)
-                self.robot.push_command()
+                for joint in self.robot.head.joints:
+                    self.robot.head.move_by(joint, 0.0)
+                for joint in self.robot.end_of_arm.joints:
+                    self.robot.end_of_arm.move_by(joint, 0.0)
 
             self.robot.pimu.runstop_event_trigger()
         else: