Laravel 5.6 updates

Travis config update

Removed HHVM script as Laravel no longer support HHVM after releasing 5.3

vendor/symfony/finder/SplFileInfo.php

@@ -26,7 +26,7 @@ class SplFileInfo extends \SplFileInfo
      * @param string $relativePath     The relative path
      * @param string $relativePathname The relative path name
      */
-    public function __construct($file, $relativePath, $relativePathname)
+    public function __construct(string $file, string $relativePath, string $relativePathname)
     {
         parent::__construct($file);
         $this->relativePath = $relativePath;