Add virsh testcase virsh_save_image_edit

domain/virsh_save_image_edit.cfg
domain/virsh_save_image_edit.py

Signed-off-by: Guannan Ren <gren@redhat.com>
Merge pull request #43 from Guannan-Ren/save_image_edit

Add virsh command testcase virsh_save_image_edit