Add convert_metric nodes to depth_registered.launch.xml (Indigo)

Tested successfully with ROS Indigo on Ubuntu 14.04

Note that the kinect does not work out of the box with the openni packages in Indigo, I had to follow the directions given here: http://www.pcl-users.org/Can-t-use-Kinect-in-Ubuntu14-04-tp4033666p4035318.html

Namely, compile and install Openni version 1.5.4.0 from https://github.com/OpenNI/OpenNI/releases and SensorKinect v0.93-5.1.2.1 from https://github.com/avin2/SensorKinect/releases

Fixes #11