core: Set disk alias and description on register disk

Setting the disk alias name and description from the disk's meta data,
once it is being registered again.

Change-Id: If65018fef71fa126173ab516a89e8bd158b06f7e
Bug-Url: https://bugzilla.redhat.com/1047623
Signed-off-by: Maor Lipchuk <mlipchuk@redhat.com>