Save some more image attributes to volume_glance_metadata.

Current issue: When copying an image to a volume, attributes like size, disk_format, container_format,
checksum, min_disk and min_ram have not been copied so far. When booting a VM from a volume, we are
not able to check these atrributes without giving the image id. Furthermore, if the original
image is deleted, we will lose all the information.

This patch saves these attributes into volume_glance_metadata. We can still check these attributes
without giving the image id when booting a VM from a volume.

Fixed Bug 1159824.

Change-Id: I42ce676026d32be6e3f4bec6fd269908e2df0a8c