Fix pluggable ee errors

stretch_core/nodes/command_groups.py

@@ -140,9 +140,9 @@ class WristYawCommandGroup(SimpleCommandGroup):
 
 class GripperCommandGroup(SimpleCommandGroup):
     def __init__(self, range_robotis=None, node=None):
+        self.gripper_conversion = GripperConversion()
         SimpleCommandGroup.__init__(self, 'joint_gripper_finger_left', range_robotis, acceptable_joint_error=1.0, node=node)
         self.gripper_joint_names = ['joint_gripper_finger_left', 'joint_gripper_finger_right', 'gripper_aperture']
-        self.gripper_conversion = GripperConversion()
         self.update_joint_range(range_robotis)
 
     def update_joint_range(self, joint_range, node=None):

stretch_core/nodes/joint_trajectory_server.py

@@ -1,6 +1,8 @@
 #! /usr/bin/env python
 from __future__ import print_function
 
+import importlib
+
 import rospy
 import actionlib
 from control_msgs.msg import FollowJointTrajectoryAction