refs #4631 started to work on installing updates during installation in case we reuse existing tables. Problem: In case there are updates available and one of those updates writes a config the installer thinks we are already done. Therefore we do now create the config file as early as possible and before the install the updates. We create the config file once we have the database information. Also allows us to remove the db_infos session hack. While installation is in progress we set a flag in General currently named install_in_progress (tbd)
Merge branch 'master' of github.com:piwik/piwik

Conflicts:
	tests/PHPUnit/UI