Launch file for playing back raw data

[jonbinney]

Should be possible to record just camera/depth/image_raw and camera/rgb/image_raw, at 3 bytes/pixel, then play it back like a running system.
Blocked on separate debayer nodelet.

Migrated over from https://kforge.ros.org/openni/trac/ticket/18

[jonbinney]

This should now be possible by launching the appropriate nodelets. I'm not planning on adding a sample launchfile to do this, but if someone contributes one I'd be happy to merge it in.