Make camera work in a librviz node

[lucasw]

Last time I tried I couldn't make a node that used the rviz library ( http://docs.ros.org/kinetic/api/librviz_tutorial/html/index.html ) to render the camera output.

It's worth trying again, also add example source code to this project that shows it either working or not.

If it doesn't work raise the issue in the rviz repo and debug.

[lucasw]

This node could be made very useful and generic by adding a service interface to add any rviz plugin, and configure it (which regular rviz ought to have anyhow, but this would be a good demonstration).