Shore up the implementation of copyfile_sparse

Signed-off-by: Chris Lalancette <clalancette@gmail.com>
Make the RPM spec file depend on libvirt-daemon-config-network

As pointed out by giulivo, current RPM distributions
will not start the default network without
libvirt-daemon-config-network installed.  While it is
possible to use Oz without this default network, I think
that most users would be happier to have it installed.
Make oz depend on libvirt-daemon-config-network.

Signed-off-by: Chris Lalancette <clalancette@gmail.com>