Libvirt provider

Adding Packer Qemu builder:
* Packer/answer_files/*_virtio: Install the virtio drivers from the ISO (NOT provided)
* windows_*.json needs some manual tweaks to match the virtio drivers ISO path

Adding Vagrant-libvirt provider:
* Uses the QEMU qcow2 images provided by packer to build the DetectionLab
* Vagrantfile needs manual tweaking to match libvirt's host configuration (backing store, network interfaces, etc)

README:
* Added separate README with instructions for libvirt

Terraform/locals.tf

@@ -4,4 +4,3 @@ locals {
   ata_url       = "https://${aws_instance.wef.public_ip}"
   guacamole_url = "http://${aws_instance.logger.public_ip}:8080/guacamole"
 }
-