Provide an easier way for modules to delay firing after upgrade

Althought the documentation clearly indicates that first an upgrade must be done, and then an update of the project, this theory is much different in practise. Upgrading and Updating a project in 80% is done simultaneosly. It is still possible to do this, however this is less clear how to do this if proper tags are not set and to do this without a restart.
With a small addition, an upgrade module can specify that it should only fire after an upgrade has already finished.