Update Rhel7.ks.cfg kickstart-based installation with LVM filesystem

Rhel 7 Kickstart file with a little kickof hardening by disabling unnecessary services especially in /etc/sysctl.conf
A default login banner for GUI and ssh logins is enabled to warn users they are monitored
Filesystem is also lvm-based so that a full filesystem can be extended with further space added anytime with the lvm utility