WIP: Vhost0 management integration.

Removing systemd networking configuration at RHEL8 jeopardized Contrail Virtual Router deployment (https://github.com/Juniper/contrail-vrouter ) - multiple CNI are based on this project. Problem is in configuring vhost0 - layer3 interface , used between host OS and Vrouter itself. It is being configured with systemd now , but for newest RHEL major release this functionality should be moved to NetworkManager. This will also benefit recent problems we had with OpenShift which also uses NM.

Documentation was added into README.md , for new functinality testing - just follow it , creating of vhost0 interface is expted as successfull result.