tests.jumbo:Fix get_linux_ifname() error

get_linux_ifname() has been moved from utils_test into utils_net.
But the commit 7db6cc4db5ba5d86659839b4afee96603c346520
change it back to utils_test for linux.

Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
libvirt_vm: Add exists() for libvirt VM class.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
virsh: Add migrate_setmaxdowntime method.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
libvirt.test: Add test module for virsh migrate-setmaxdowntime.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
Merge pull request #497 from QiuMike/tests.jumbo_Fix_get_linux_ifname()_error

tests.jumbo:Fix get_linux_ifname() error
Merge pull request #488 from yumingfei/virsh_migrate_setmaxdowntime

Libvirt:Virsh migrate setmaxdowntime
virt.test: fix some netperf issues

this patch:
1.fix the issue netperf cannot login with two nics,
2.add  netperf test support tcp_crr protocol
3.add an automated way to get the cdrom drive number.
4.modify the file path of netperf.tar.gz. now should
put the src file under "virt/shared/deps"
5.add more step info