Description:
------------
When a proxy is used with the following code. The proxy is not used.

Problem is in that the proxy_port is a string type. When the port is type casted to an int it will work.

Reproduce code:
---------------
$client = new SoapClient(null, array('proxy_host'     => "localhost",
                                            'proxy_port'     => '8080',
                                            'login'    => "user",
									        'password' => "test",
											'uri'            => 'mo:http://www.w3.org/',
											'location'       => 'http://some.url'));

echo $client->__doRequest('<?xml version="1.0" encoding="UTF-8"?>...etc',
'http://some.url',
"add",
'1.2');

Expected result:
----------------
That the proxy will receive the request.

Actual result:
--------------
The call is done without the use of the proxy.