Added a node to compress the D435i images

vz_ros_wrappers/launch/D435i_and_Lepton.launch

@@ -1,6 +1,8 @@
 <launch>
       <node pkg="vz_ros_wrappers" type="grab_D435i.py" name="D435i" />
       <node pkg="vz_ros_wrappers" type="grab_thermal.py" name="FLIRLepton" />
+      <node pkg="image_transport" type="republish" name="D435iCompressed"
+            args="raw in:=/D435i/image_raw compressed out:=/D435i/image_raw" />
       <!-- Flip images and display when collecting data? -->
       <param name="flip_images_grab_data" type="bool" value="true" />      
   </launch>