Get gerrit events from RabbitMQ as message queue service

This patch adds implementation of MessageQueueListener extension in
RabbitMQ Consumer Plugin.

https://wiki.jenkins-ci.org/display/JENKINS/RabbitMQ+Consumer+Plugin

Using this feature, we can trigger job by gerrit event in message queue.
Merge pull request #151 from rinrinne/rabbitmq

Get gerrit events from RabbitMQ as message queue service