playbook: Use vifib-kernel to upgrade debian server kernel to latest version

Add option to upgrade kernel to vifib upgrader Upgrade kernel of debian8 and debian9 to linux-image-4.9.0-0.bpo.5-amd64. Upgrade debian7 to debian 8 (then kernel can be upgraded)

The command line with upgrade kernel will be:

ansible-playbook upgrader-run.yml --extra-vars "upgrader_playbook=vifib-kernel-upgrade.yml" -i hosts