Fixing how errors are aggregated when sending multi transfers. Adding is...

...Redirect() flag to requests.

Refactoring how exceptions are buffered in a multi-transfer so that the following case now works correctly:

```php
<?php

require 'vendor/autoload.php';

$urls = array(
    'http://google.com',
    'https://www.facebook.com',
    'http://www.youtube.com',
    'http://www.google.com/foo',
);

$client = new \Guzzle\Http\Client();

try {
    $requests = array();
    foreach ($urls as $r) {
        $requests[] = $client->get($r);
    }
    $client->send($requests);
} catch (\Guzzle\Http\Exception\MultiTransferException $e) {
    foreach ($e as $ex) {
        echo spl_object_hash($ex) . ' ' . $ex->getMessage() . "\n\n";
    }
    foreach ($e->getFailedRequests() as $r) {
        echo "Failed: {$r->getUrl()}, {$r->getResponse()->getStatusCode()}\n";
    }
    foreach ($e->getSuccessfulRequests() as $r) {
        echo "Success: {$r->getUrl()}, {$r->getResponse()->getStatusCode()}\n";
    }
}
```

See: https://groups.google.com/forum/?hl=en#!topic/guzzle/1hhbCcHDeKE