utils_v2v: Enhancements to Target and LinuxVMCheck classes.

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

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
libvirt.tests: Add test module for v2v with partition pool.

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