Listener AMQP authentication error

Listener raises an error:

```
13:05:05 listener.1 | /opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/amq-client-1.0.0/lib/amq/client/async/adapters/event_machine.rb:164:in `block in initialize': AMQP broker closed TCP connection before authentication succeeded: this usually means authentication failure due to misconfiguration. Settings are {:host=>"localhost", :port=>5672, :user=>"bithub", :pass=>"[filtered]", :auth_mechanism=>"PLAIN", :vhost=>"bithub", :timeout=>nil, :logging=>false, :ssl=>false, :broker=>nil, :frame_max=>131072, :heartbeat=>0, :scheme=>"amqp"} (AMQP::PossibleAuthenticationFailureError)
```

Start with the listener entry point and the authentication error reported from amq-client's event_machine.rb:164; compare the displayed host, port, user, vhost, and authentication settings with the broker configuration. Done means the listener authenticates successfully without raising AMQP::PossibleAuthenticationFailureError.

Written by the indexing model from the issue text.