add start_debug_demo.launch,

http://wiki.ros.org/tf/Tutorials/Debugging%20tf%20problems using start_debug_demo.launch, but it is not find in this pakcage, add launch file and c++ program that users can follow the tutorial.

We also need to correct tutorial, because it seems error massage have been updated

c.f. http://wiki.ros.org/tf/Tutorials/Debugging%20tf%20problems