enable finder search follow link files and directories

If I have many classes in different directories, I can create a directory, create files and directories link in it. Add this method, swagger-php will follow this structure as well.

src/Util.php

@@ -75,7 +75,7 @@ public static function finder($directory, $exclude = null)
             $finder = new Finder();
             $finder->sortByName();
         }
-        $finder->files()->name('*.php');
+        $finder->files()->followLinks()->name('*.php');
         if (is_string($directory)) {
             if (is_file($directory)) { // Scan a single file?
                 $finder->append([$directory]);