Id 0 == False

When checking if we have a song id, we should check against None (id ==
None).  Doing "if id" will return False when id is 0.

ocarina/label.py

@@ -48,7 +48,7 @@ class AttrLabel(gtk.Alignment):
 		global lib_find_id
 		global lib_get_attr
 		id = lib_find_id(filepath)
-		if id:
+		if id != None:
 			text = str(lib_get_attr(id, self.attr))
 			if self.other:
 				text = "%s %s" % (self.other, text)