HTML matrix report: show apps if constellation has no name

[jernst]

In the HTML matrix report, the headers of the colums are supposed to be the names of the respective constellations.

If a constellation is not named -- e.g. if we are running a generic SaaSDriver -- it currently shows "Unnamed", which is not so great. I am changing this to show the NodeDrivers and their roles involved, which is marginally better but only marginally.

We should show the apps involved, but that needs more coding than I want to be distracted to right now because the apps can be run-time parameters provided by the user, rather than be in the test plan as the current code assumes.