Update datenstand for BLW layer

git-svn-id: https://svn.bgdi.admin.ch/tilegenerator/trunk@471 bd729b38-e83c-4c31-ba7f-6b5d0bf862be
use the right timestamp for BLW

git-svn-id: https://svn.bgdi.admin.ch/tilegenerator/trunk@472 bd729b38-e83c-4c31-ba7f-6b5d0bf862be