Laravel 5.6 updates

Travis config update

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

vendor/symfony/routing/Tests/Fixtures/php_dsl_sub.php

@@ -6,6 +6,7 @@ return function (RoutingConfigurator $routes) {
     $add = $routes->collection('c_')
         ->prefix('pub');
 
+    $add('root', '/');
     $add('bar', '/bar');
 
     $add->collection('pub_')