Files with certificates are created with incorrect permissions by install_demo_configuration.sh script

The script install_demo_configuration.sh creates certificates (and corresponding keys) which are stored in files with incorrect permissions. Current permissions:

-rw-rw-r-- 664 esnode-key.pem
-rw-rw-r-- 664 esnode.pem
-rw-rw-r-- 664 kirk-key.pem
-rw-rw-r-- 664 kirk.pem
-rw-rw-r-- 664 root-ca.pem

Required permissions should be 600