Set friendly names for validation attributes in Laravel 4

gistfile1.php

$rules = array(
	'username'       => 'required|min:8|unique:users|integer',
	'firstname'      => 'required',
	'lastname'       => 'required',
	'email'     	 => 'required|email',
	'password'		 => 'required|confirmed'
);

$messages = array(
    'required' => 'El campo :attribute es obligatorio.',
    'email.required' => 'El campo de :attribute es requerido y debe ser una dirección válida.',
    'validation.confirmed' => 'Las contraseñas no coinciden.'
);

$friendly_names = array(
	'firstname' => 'Nombre',
	'lastname' => 'Apellido'
);

$validator = Validator::make(Input::all(), $rules, $messages);

$validator->setAttributeNames($friendly_names);