autotest/autotest — pull request #402 by ypu (2012-06-19 10:05:38+00:00)
Title: virt: Use get_image_filename to get the snapshot and base file name

The file name for snapshot and base image in QemuImg class of
virt_storage should get by function get_image_filename but not
get_path.

Signed-off-by: Yiqiao Pu