Laravel 5.6 updates

Travis config update

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

vendor/symfony/http-foundation/File/File.php

@@ -31,7 +31,7 @@ class File extends \SplFileInfo
      *
      * @throws FileNotFoundException If the given path is not a file
      */
-    public function __construct($path, $checkPath = true)
+    public function __construct(string $path, bool $checkPath = true)
     {
         if ($checkPath && !is_file($path)) {
             throw new FileNotFoundException($path);