add nicer meshes to kuka_with_gripper.sdf and add kuka_with_gripper2.sdf that can rotate without messing up IK

fix tray/tray_textured4.obj and tray/tray.urdf
fix kuka_with_cube.py
allow both IK /end-effector control and joint-space control in kuka environment, use 1./240. sec. step and 150 solver iter
bump up pybullet to 1.1.7

examples/pybullet/gym/kukaJointSpaceGymEnvTest.py

@@ -0,0 +1,23 @@
+
+from envs.bullet.kukaGymEnv import KukaGymEnv
+import time
+
+
+environment = KukaGymEnv(renders=True)
+environment._kuka.useInverseKinematics=0
+  
+motorsIds=[]
+for i in range (len(environment._kuka.motorNames)):
+  motor = environment._kuka.motorNames[i]
+  motorJointIndex = environment._kuka.motorIndices[i]
+  motorsIds.append(environment._p.addUserDebugParameter(motor,-3,3,environment._kuka.jointPositions[i]))
+
+while (True):
+    
+  action=[]
+  for motorId in motorsIds:
+    action.append(environment._p.readUserDebugParameter(motorId))
+  
+  state, reward, done, info = environment.step(action)
+  obs = environment.getExtendedObservation()
+  time.sleep(0.01)