AMQPUrlReceiver changes to support RabbitMQ >= 3.3

[anjackson]

As of version 3.3, RabbitMQ no longer supports channel.flow{active=false} and so the AMQPUrlReceiver module is lot able to use this method to pause message consumption. This patch:

• Switches to a consume/cancel model so the UrlConsumer only runs when the crawl is running.
• Separates consumption from the StarterRestarter, making both more robust.
• Prevents unanticipated exceptions from killing the StarterRestarter thread.
• Enables the durability and auto-delete features of the queues to be modified via Spring.

[nlevitt]

Seems to be working for me. Thanks!

[anjackson]

Thanks! I should have probably made it clear that we are running this at scale (UK domain crawl) on a almost-HEAD version of H3 and it's working fine.