[RFC] Hotplug APIs for qemu_vm and qemu_monitor

Hi, there, 
This is a rfc patchset for the interfaces of hotplug operation for qemu_vm.

cc @ldoktor and @ypu, comment welcomed.

Test result:
For HMP monitor:
```
SETUP: PASS (1.91 s)
DATA DIR: /var/lib/virt_test
DEBUG LOG: /home/virt-test/logs/run-2013-02-21-19.52.02/debug.log
TESTS: 4
(1/4) block_hotplug.block_virtio.one_pci.fmt_qcow2: PASS (57.55 s)
(2/4) block_hotplug.block_virtio.one_pci.fmt_raw: PASS (139.44 s)
(3/4) block_hotplug.block_virtio.multi_pci.fmt_qcow2: PASS (131.33 s)
(4/4) block_hotplug.block_virtio.multi_pci.fmt_raw: PASS (183.70 s)
TOTAL TIME: 512.05 s (08:32)
TESTS PASSED: 4
TESTS FAILED: 0
SUCCESS RATE: 100.00 %
```

For QMP monitor:
```
SETUP: PASS (1.90 s)
DATA DIR: /var/lib/virt_test
DEBUG LOG: /home/virt-test/logs/run-2013-02-20-20.23.51/debug.log
TESTS: 4
(1/4) block_hotplug.block_virtio.one_pci.fmt_qcow2: PASS (60.88 s)
(2/4) block_hotplug.block_virtio.one_pci.fmt_raw: PASS (89.07 s)
(3/4) block_hotplug.block_virtio.multi_pci.fmt_qcow2: PASS (68.84 s)
(4/4) block_hotplug.block_virtio.multi_pci.fmt_raw: PASS (115.18 s)
TOTAL TIME: 333.99 s (05:33)
TESTS PASSED: 4
TESTS FAILED: 0
SUCCESS RATE: 100.00 %
```

Qingtang Zhou (6):
  virttest.qemu_vm: Add a new list for supported devices
  Qemu Test: pci_hotplug: Update this test case
  virttest.qemu_monitor: Add APIs for device hotplug/unplug
  virttest.qemu_monitor: Verify hmp cmd in qmp as well
  virttest.qemu_vm: Add APIs for pci hotplug
  Qemu Test: pci_hotplug: Update this test with new interface

 qemu/tests/cfg/nic_hotplug.cfg |  10 +-
 qemu/tests/pci_hotplug.py      | 359 ++++++++++++++++++++++------------------
 tests/cfg/block_hotplug.cfg    |  42 +++--
 virttest/qemu_monitor.py       | 368 ++++++++++++++++++++++++++++++++++++++++-
 virttest/qemu_vm.py            |  90 ++++++++--
 5 files changed, 668 insertions(+), 201 deletions(-)