added Str alias.

app/config/app.php

@@ -168,6 +168,7 @@ return array(
 		'Schema'          => 'Illuminate\Support\Facades\Schema',
 		'Seeder'          => 'Illuminate\Database\Seeder',
 		'Session'         => 'Illuminate\Support\Facades\Session',
+		'Str'             => 'Illuminate\Support\Str',
 		'URL'             => 'Illuminate\Support\Facades\URL',
 		'Validator'       => 'Illuminate\Support\Facades\Validator',
 		'View'            => 'Illuminate\Support\Facades\View',