apply more sane permissions on cache directories

src/app/startup.sh

@@ -42,7 +42,8 @@ for d in cache lock feed-icons plugins.local themes.local; do
 done
 
 for d in cache lock feed-icons; do
-	chmod -R 777 $DST_DIR/$d
+	chmod 777 $DST_DIR/$d
+	find $DST_DIR/$d -type f -exec chmod 666 {} \;
 done
 
 chown -R $OWNER_UID:$OWNER_GID $DST_DIR \