Honour passive option in rabbitmq input plugin

The queue declare command was not honouring the setting of passive so a user without write access could not run the AMQP input plugin.  This fixes LOGSTASH-1461.

I've tested by building the jar, copying it over to /opt/logstash/server/lib, restarting and observing the output of tcpdump.  The queue declare method call now sets the passive bit correctly, and messages are even being consumed now.