Checker for ELB

This file is need for Amazon's ELB to know this cluster's instance is up and responding. If not, the ELB discards the instance from cluster.

http://mf-geoadmin30t.bgdi.admin.ch/checker
http://mf-geoadmin30i.bgdi.admin.ch/checker
http://mf-geoadmin3.bgdi.admin.ch/checker

should answer 'OK'