build: test for topological ordering with underlays

[wjwwood]

Just like this catkin_make_isolated issue:

ros/catkin#590

[jbohren]

Potential plan for CMake packages:

• scrape packages in current workspace and extended workspaces based on .catkin file to determine packages in each workspace
• generate a list of packages whose locations have changed since the last build
• force CMake to clear cache variables like ${PKG_NAME_DIR} with the unset argument -UPKG_NAME_DIR and reconfigure

This will also enable a report of where catkin dependencies are coming from in a system.