Deep scan result deduplication

Multiple deep scan will touch the same path, and UI filter same result
by name/distro/version tuple. So constructing link with UUID result in
same path mapping to different link. Change it to use path md5 so that
UI can filter same result.

Signed-off-by: Royce Lv <lvroyce@linux.vnet.ibm.com>
Deep scan: Adding scan ignore path

Exclude kimchi constructed path to avoid duplicate scan of scan result.
In the future, more ignore path will be added due to performance.

Signed-off-by: Royce Lv <lvroyce@linux.vnet.ibm.com>
Deduplication: deduplication in shallow scan

Shallow scan reported scan result in format of "pool name" plus "volume name",
this resulted in deep scans same result appears to be many times in shallow scan.
Just report volume name in shallow scan.

Signed-off-by: Royce Lv <lvroyce@linux.vnet.ibm.com>
Nit fix of scan_dir_prepare

Delete redundant param in scan_dir_prepare().

Signed-off-by: Royce Lv <lvroyce@linux.vnet.ibm.com>