Add a method named 'sync' to VMXML class.

Lots of times to call vmxml.undefine() and vmxml.define(), to
make our config in vmxml take effect in vm.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
Add test for svirt attach disk.

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>
libvirt_svirt: Add test for some domain operations.

Test the operations with svirt.

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>
Add add_security method in make_create_command method to add '--security'

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>
Add test for svirt in virt-install.

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>
Add filter in guest-os to allow svirt_install access it.

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>