virttest.qemu_monitor: Update send_args_cmd command.

Fix bug that it could not return correct result for some commands.
Also update the place for command line recording.

Signed-off-by: Feng Yang <fyang@redhat.com>
virttest.remote : make remote scp support ipv6 address

This patch make remote scp related func support ipv6 address.

Signed-off-by: Yunping Zheng <yunzheng@redhat.com>