This base connection object will be used to simplify the API in various
places, reduce libvirt API calls, and better share code between virtinst
and virt-manager. For now it just centralizes connection opening.
This also exposed various places where our handling for older libvirt
was busted, so raise our minimum host version to 0.6.0, the first
version that supports threaded client requests.
Despite being a known quantity, autotools is so overkill for our needs,
so let's drop it and replace it with a much simpler and easy to customize
system.
Cole Robinson