Bump Bunny to 1.1.7+

Fix a thread leak which affects apps that perform
manual recovery, including Logstash RabbitMQ plugin.

Plus this kind of latency improvements:

![](https://f.cloud.github.com/assets/1800798/2175168/ac09c4dc-95ba-11e3-93d9-a28fb25a8327.png)
Merge pull request #1190 from michaelklishin/patch-5

[rabbitmq] Bump Bunny to 1.1.7+
Merge git://github.com/logstash/logstash