[virt-tools-list] Introducing: virtlib library

[Darryl L. Pierce]

The goal of the virtlib library is to extract from Virt Manager and
Virt Manager TUI the shared business logic and package it separately
as a reusable library of code.

This first patch set creates the library's package structure and
defines the first shared business object: the Hypervisor model.

A concrete implementation, KvmHypervisor, interacts with libvirt
and provides the source for information presented by both version of
Virt Manager to the user as well as enable controlling networks,
storage pools and domains.

Future enhancements will provide the means for retrieving physical
storage details and other information needed by Virt Manager.