Bug 20107 add array params

Updates HTTP_OAuth to parse multiple parameters into array values and to include multiple array values when creating signatures.

Considering the query string `ids[]=1&ids[]=2&ids[]=3`, to set or get array params, use:

```php
<?php

// get parsed array params for provider request
$params = $request->getParameters();
var_dump($params['ids[]']); // array('1', '2', '3');
var_dump($request['ids[]']); // array('1', '2', '3');

// using the $additional array parameter for consumer methods
$consumer->getRequestToken('http://myservice.com', 'oob', array('ids[]' => array(1, 2, 3)));

?>
```