[TYPO3-v4] install tool bashing

[Sebastian Michaelsen]

> 4) "Visit the Frontend" link is stupid, as there is no template yet. So
> the result would be "No Template found" error message. Not a very nice
> welcome to the CMS, right? In the intro-package it is ok, because the
> frontend already looks very nice. But on a regular 1-2-3 installation it
> does not.
Despite improvements to the installer, the "no template" handling could 
be improved. If it's a fresh install (e.g. check if there are pages in 
the database) don't throw an error but display a welcome screen like 
"Intallation of TYPO3 was successful. Please log in to the Backend and 
create a template".