qemu.tests: Add a new test: Migrate after NIC hotplug

commit 9eaa33dd1abe85141d2eee48c9712c69dcb4edff
    Author: Yiqiao Pu <ypu@redhat.com>
    Date:   Mon Aug 1 11:15:22 2011 +0000

    KVM-test: Add a new test: Migrate after NIC hotplug

    https://tcms.engineering.redhat.com/case/69571/?from_plan=3083

    Migrate VM which was hotpluged a nic, and test if new nic works.
    This test reuses nic_add()/nic_del()/netdev_add()/netdev_del()
    in nic_hotplug.py, need put them the kvm_test_utils.py later.
    This test only works with latest qemu-kvm.

    Signed-off-by: Yiqiao Pu <ypu@redhat.com>

    commit 324c09e2302a785893bc4a20ea79a24b2fa81a29
    Author: Qingtang Zhou <qzhou@redhat.com>
    Date:   Tue Jun 26 16:38:50 2012 +0000

    virt: Update 'guest_name' to 'os_type' in all scripts

    Checking guest os type with 'guest_name' parameter may not
    always work for all guests, and not supported by upstream.
    Thus update all these places to using 'os_type'.

    RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=835505

    Signed-off-by: Qingtang Zhou <qzhou@redhat.com>
    Acked-by: Yiqiao Pu <ypu@redhat.com>

    commit a54f0381cb8703efeb72f43a684e11e733215bdf
    Author: Feng Yang <fyang@redhat.com>
    Date:   Fri Dec 21 08:57:27 2012 +0000

    migration_after_nichotplug.py: update it with vm.hotplug_nic()

    Use VM's hotplug_nic() function.
    Update step docs and error.context()
    Make this script works again.

    BZID:
    Bug 874433 - [KVM_Autotest] nic_hotplug.migration: Please update your code
     to use VirtNet.generate_mac_address()
    Bug 889390 - [KVM_AUTOTEST] Update migration_after_nichotplug.py to reuse
     some framework function.

    Signed-off-by: Feng Yang <fyang@redhat.com>
    Acked-by: Qingtang Zhou <qzhou@redhat.com>

Send this script to upstream.
Signed-off-by: Feng Yang <fyang@redhat.com>
nic_hotplug.cfg: Add migration_after_nichotplug test case.

Signed-off-by: Feng Yang <fyang@redhat.com>