add d435i sleep

stretch_core/nodes/d435i_configure

@@ -42,7 +42,8 @@ class D435iConfigureNode:
             )
 
     def main(self):
-        rospy.init_node('configure_d435i')
+        rospy.sleep(3) # sleep for 3 seconds to wait for D435i to be ready
+	rospy.init_node('configure_d435i')
         self.node_name = rospy.get_name()
         rospy.loginfo("{0} started".format(self.node_name))
         self.parameter_client = dynamic_reconfigure.client.Client('/camera/stereo_module/')