spawn laser filter on c2 (where the rest of the pipeline runs)

Without this, all tilt laserscans are sent back and forth between
c1 and c2 for no reason, adding to the general delays...

pr2_navigation_perception/lasers_and_filters.xml

@@ -12,7 +12,7 @@
   <rosparam command="load" file="$(find pr2_navigation_perception)/config/point_cloud_footprint_filter.yaml" />
 </node>
 
-<node pkg="laser_filters" type="scan_to_scan_filter_chain" name="interpolate_missing_tilt_laser_data_filter">
+<node pkg="laser_filters" type="scan_to_scan_filter_chain" name="interpolate_missing_tilt_laser_data_filter" machine="c2">
   <rosparam command="load" file="$(find pr2_navigation_perception)/config/laser_interpolation.yaml" />
   <remap from="scan" to="tilt_scan" />
   <remap from="scan_filtered" to="tilt_scan_interpolated" />