d/g-d.post{inst,rm}: adding postinst and postrm script

For automated use of a centralized project directory we will use a
seperated group 'gridvis-desktop' that will be generated or removed by
the postinst/postrm scripts.
d/g-d-w.sh: expanding the starter script

The starting script is expaneded to do some sanity checks after adding
the the implementation of the postinst/postrm scripts.