pad tracknumbers with leading zeroes (Debian #655079)

Ensures that tracknumbers are zero-padded to two digits.
That seems to be common usage.

Bug-Debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=655079
From: martin f krafft <madduck@debian.org>

src/tools/cuetag.sh

@@ -64,8 +64,8 @@ vorbis()
 	TITLE='%t'
 	VERSION=''
 	ALBUM='%T'
-	TRACKNUMBER='%n'
-	TRACKTOTAL='%N'
+	TRACKNUMBER='%02n'
+	TRACKTOTAL='%02N'
 	ARTIST='%c %p'
 	PERFORMER='%p'
 	COPYRIGHT=''