move timezone set into core bootstrap.

laravel/laravel.php

@@ -7,13 +7,6 @@
  */
 require 'core.php';
 
-/**
- * Register the default timezone for the application. This will be the
- * default timezone used by all date / timezone functions throughout
- * the entire application.
- */
-date_default_timezone_set(Config::get('application.timezone'));
-
 /**
  * Register the PHP exception handler. The framework throws exceptions
  * on every error that cannot be handled. All of those exceptions will