libvirt.test: Add 'running,paused,verbose' option for virsh managedsave

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>
virsh_destroy: add case to test --graceful option.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Merge pull request #91 from yangdongsheng/virsh_destroy

virsh_destroy: add case to test --graceful option.
Merge pull request #84 from liyangfnst/managedsave

libvirt.test: Add 'running,paused,verbose' option for virsh managedsave
Merge pull request #90 from vanbogithub/bfan-dev

guestfish_block_dev: Split image preparation from individual test case