Implement all magic methods for Alert sort

Ticket:	#4631
Add pxe-config.sh script for quickly booting Free*, True* ISOs.
Supports both Interactive and non-Interactive processing methods.
Interactive mode (executed without arguments) strives to keep the
interface simple and straight forward. Can also be run via cron
for regularly scheduled maintenance on ISOs in the images dir.

(cherry picked from commit 6dacdcc2f65d2cd258d9534aafa492c43994a12f)
Create an rrd system dataset
Use system dataset for rrd graphics

Ticket: #4634