Fix permissions of /etc/ssh/ssh_known_hosts
Fix permissions of /etc/ssh/ssh_known_hosts

This is being created with 0600 permissions in some cases (probably down
to a default umask).

this explicitly sets the permissions so that it can be used by all users
on the system.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet