virttest.libvirt_vm: Add functions to get device details.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
utils_test: Add functions for remote disk operations.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
utils_test: Support lvm for RemoteDiskManager.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
utils_test.libvirt: Add attaching operations for libvirt vm.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
utils_test.init: Add function for RemoteDiskManager.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
virt: Fix a bug in RemoteFile init

If remote file doesn't exist, SCPTransferFailedError
will be catched, and then creat a new empty file om
local host.

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>
Merge pull request #1610 from yumingfei/disk_operations

Add some functions for disk operations
virt: add truncate() func into RemoteFile class

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>
Merge pull request #1693 from liyangfnst/remote_file

virt: Fix 2 bugs in RemoteFile class
Add disk xml options and functions.

    Add os loader bios options in xml.
    Add interface driver option in xml.
    Add more disk options(wwn, serial, vendor, product, blockio, geometry) in xml.
Merge pull request #1673 from rbian/disk-options

Add more disk options in xml. Modify function to get disk option in xml.