virttest.virsh: Add pool_build function.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
virttest.libvirt_storage: Add StoragePool class.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
v2v.tests: Add test for converting remote host's vms.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>