cddb_daemon: Various fixes.

 * Add ".wav" to the ends of filenames
 * Add a track number at the beginning of the filename, e.g. "01"
 * Don't hard-fail if the FreeDB response contains an invalid year

Signed-off-by: Jérôme Duval <jerome.duval@gmail.com>
file_systems/cdda: avoid leaking the attributes fd.

* see bug #9528.
file_systems/cdda: Various fixes.

 * When restoring shared attributes, don't affect CDDB:lookup status
 * Volume renames should not affect CDDB:lookup status, only file renames should

This fixes some of the "cddb_daemon not updating CD info" problems.

Signed-off-by: Jérôme Duval <jerome.duval@gmail.com>