- Add CIS 1.3 benchmark for RHEL/CentOS 6

Note this will require adding the following to the <syscheck> config to activate:

    <system_audit>/var/ossec//etc/shared/cis_rhel6_linux_rcl.txt</system_audit>

Definitions in this update support Redhat, Centos, Oracle, Cloudlinux and Betterlinux 6