Description:
------------
AMQPEnveloppe#body is not binary safe, so it cant contain NULL byte, which is 
embarrassing when you deal with PHP serialization format which may contain NULL 
bytes aka : a serialized object

Test script:
---------------
<?php

class Foo { private $bar="bar"; }

$c = new AMQPConnection(/* params */);
$c->connect();
$channel = new AMQPChannel($c);

$ex = new AMQPExchange($channel);
$ex->setName('test');
$ex->publish(serialize(new Foo), 'test');

$q = new AMQPQueue($channel);
$q->setName('test');
var_dump($q->get());

Expected result:
----------------
string(39) "O:3:"Foo":1:{s:8:"Foobar";s:3:"bar";}"

Actual result:
--------------
The result gets truncated at the first NULL byte met, thus the unserialize() will 
fail.

string(18) "O:3:"Foo":1:{s:8:""