We can't use a core application here, as in case of we can't
connect to the update server, we would try to pop up a message
box. This fails and crashes cause we have no gui application.
Introduce some magic marker to differentiate between update and
package management modus. The base installer now needs explicite
arguments passed to make the app an updater or package manager.
Adjustment some more classes to take the new markers into account.
