virt: add nodedev_xml into libvirt_xml module.

nodedev_xml for node device refer to http://libvirt.org/formatnode.html.

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>
virt: add some test for nodedev xml in libvirt_xml_unitest.

testNodedevXML, testgetter, testcap

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>
virt-libvirt_vm: add a method get_key2value_from_key2path in libvirt_vm module.

Get the values stored in files whose path is in key2path_dict.
And return a dict contain key and the value in files.

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>
virt-virsh: add a method for nodedev-dumpxml and nodedev-list.

def nodedev_dumpxml(name, **dargs):
    """
    Do dumpxml for node device.

    @param name: the name of device.
    @return: string for xml of device.
    """
def nodedev_list(nodedev_filter=None, **dargs):
    """
    List the node devices.

    @param nodedev_filter: pattern to filter the result.
    @return: list of device name.
    """

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>
virt-libvirt: add configuration and test module for virsh nodede-dumpxml.

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