Laravel 5.6 updates

Travis config update

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

vendor/symfony/routing/Loader/PhpFileLoader.php

@@ -46,7 +46,7 @@ class PhpFileLoader extends FileLoader
 
         $result = $load($path);
 
-        if ($result instanceof \Closure) {
+        if (\is_object($result) && \is_callable($result)) {
             $collection = new RouteCollection();
             $result(new RoutingConfigurator($collection, $this, $path, $file), $this);
         } else {