With fixes for virtual networking

This should fix virtual networking (through working vif scripts) and has a better libxl backend.

Support for Debian/Ubuntu with xen-4.2

Merge pull request #43 from euanh/debian

oasis: Include linker flags needed on Debian

Now with qcow2 support

Merge pull request #34 from djs55/add-qcow2

Add qcow2 file format support