Laravel 5.6 updates

Travis config update

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

vendor/symfony/debug/Debug.php

@@ -23,7 +23,7 @@ class Debug
     /**
      * Enables the debug tools.
      *
-     * This method registers an error handler, an exception handler and a special class loader.
+     * This method registers an error handler and an exception handler.
      *
      * @param int  $errorReportingLevel The level of error reporting you want
      * @param bool $displayErrors       Whether to display errors (for development) or just log them (for production)