Added OS info support for RHEL 6.x

[chatenilesh]

Changes made in reference to RHEL 7.3 os info files.

[admin@RedHat-7 ~]$ cat /etc/redhat-release 
Red Hat Enterprise Linux Server release 7.3 (Maipo)
[admin@RedHat-7 ~]$ 
[admin@RedHat-7 ~]$ cat /etc/os-release 
NAME="Red Hat Enterprise Linux Server"
VERSION="7.3 (Maipo)"
ID="rhel"
ID_LIKE="fedora"
VERSION_ID="7.3"
PRETTY_NAME="Red Hat Enterprise Linux"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:redhat:enterprise_linux:7.3:GA:server"
HOME_URL="https://www.redhat.com/"
BUG_REPORT_URL="https://bugzilla.redhat.com/"

REDHAT_BUGZILLA_PRODUCT="Red Hat Enterprise Linux 7"
REDHAT_BUGZILLA_PRODUCT_VERSION=7.3
REDHAT_SUPPORT_PRODUCT="Red Hat Enterprise Linux"
REDHAT_SUPPORT_PRODUCT_VERSION="7.3"
[admin@RedHat-7 ~]$ 

[zcalusic]

Very nice contribution @chatenilesh, thanks a lot on your effort to fill missing RHEL 6.x bits and pieces. :+1: