Description:
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According to http://www.rabbitmq.com/resources/specs/amqp0-9-1.pdf there is no 
type 'header'. The valid exchange type is 'headers'

Test script:
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$amqp_ex = new AMQPExchange($amqp_channel);
$amqp_ex->SetName('test');
$amqp_ex->SetType(AMQP_EX_TYPE_HEADER);
$amqp_ex->declare();



Expected result:
----------------
No errors

Actual result:
--------------
PHP Fatal error:  Uncaught exception 'AMQPExchangeException' with message 'Server 
connection error: 503, message: COMMAND_INVALID - invalid exchange type 'header'' 
in ...