libvirt.test: Add abnormal resource test for some commands

These testcases test if commands executed succeed when
resource becomes to abnormal, like lack disk, cpu disable.

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>
libvirt.test: Add some more cases for abnormal resource test

1.Add virsh snapshot-create and virsh dump command test
2.Add memory_lack, disk_lack, cpu_busy, twice_execute test type

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>
libvirt.test: Add more cases(install, migration) for abnormal resource test

1.Add virt-intall and virsh migrate (--live) command test
2.Add timeout, remote network restart, readonly test type

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>
libvirt.test: Fix some problems in test code

1.Restart cgconfig and libvirtd after test to recover env
2.Set swap off before memroy test
3.Fix checkpoint after domain clone
4.Change umount action's timeout to 120s

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>
Merge pull request #211 from liyangfnst/abnormal

libvirt.test: Add abnormal resource test for some commands