libvirt: remove version checks for live snapshot feature
libvirt: remove version checks for live snapshot feature

The live snapshot feature requires libvirt 1.0.0 and QEMU 1.3.0
which are both older than our minimum required versions. Thus we
can remove the version checks for this feature.

Change-Id: I22d7545ec9d073498b070de274f5a58e32c80df5

rahulunair/nova,cloudbase/nova,sebrandon1/nova,phenoxim/nova,cloudbase/nova,alaski/nova,jianghuaw/nova,gooddata/openstack-nova,Juniper/nova,openstack/nova,mikalstill/nova,klmitch/nova,openstack/nova,vmturbo/nova,phenoxim/nova,klmitch/nova,Juniper/nova,hanlind/nova,gooddata/openstack-nova,vmturbo/nova,mikalstill/nova,mahak/nova,vmturbo/nova,mahak/nova,Juniper/nova,jianghuaw/nova,sebrandon1/nova,rajalokan/nova,hanlind/nova,vmturbo/nova,jianghuaw/nova,rajalokan/nova,jianghuaw/nova,bigswitch/nova,gooddata/openstack-nova,klmitch/nova,rahulunair/nova,rahulunair/nova,cloudbase/nova,rajalokan/nova,sebrandon1/nova,hanlind/nova,mikalstill/nova,gooddata/openstack-nova,openstack/nova,alaski/nova,bigswitch/nova,Juniper/nova,klmitch/nova,mahak/nova,rajalokan/nova