[rabbitmq] Disable automatic connection recovery for input, fixes LGOSTASH-1350

See LOGSTASH-1350.

Automatic recovery was added after the plugin was rewritten.
In logstash's case, full control over how recovery
is performed is probably more important than
removing some plugin code.
Merge pull request #641 from michaelklishin/patch-1

[rabbitmq] Disable automatic connection recovery for input, fixes LGOSTASH-1350