Do not use basic.nack (RabbitMQ extension) [AMQP-171]

[spring-operator]

Dave Syer opened AMQP-171 and commented

#1729 was a decent improvement in efficiency and performance, but it relies on basic.nack. Probably we need a way to switch that off at least.

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Affects: 1.2.0.RC1

[spring-operator]

Dave Syer commented

Moved most of the commit/rollback responsibility in SMLC to the consumer - that way it can collect delivery tags and bulk reject them if necessary.