create a simple overview page of current status

[stolpeo]

There should be a compiled list of all entities on the cluster. A simple html page with a static table should do. This is for the HPC admins, and should also simply be made available for Dieter who does not need the overhead of the HPC admin informations displayed. Maybe introduce a new type of account or reduced HPC admin entity, or more like a "head of HPC" view that displays all relevant information without administrative tasks.