libvirt_xml: Add support of net and storage for nodedev_xml.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
libvirt_xml: add implemention for hostdev in libvirt_xml/devices/.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
libvirt_xml: add a function to add hostdev device in vm_xml.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Merge pull request #1461 from yangdongsheng/pci_passthrough

libvirt: Pci passthrough