There is currently no way to determine the libvirt version of a remote
libvirtd we are connected to. This is a useful piece of data to enable
feature detection.
Implementation of tunnelled migration, using a Unix Domain Socket
on the qemu backend. Note that this requires very new versions of
qemu (0.10.7 at least) in order to get the appropriate bugfixes.
Signed-off-by: Chris Lalancette <clalance@redhat.com>