Ensure TCP_NODELAY is disabled by fixing namespacing

While using bunny-1.1.0, we discovered an unacceptable latency for publishing messages with confirmation. Between a Bunny client and broker, both running Ubuntu Precise, this latency converges to 40ms for the case of many small messages. After some head-scratching, a packet capture revealed the true cause:

![screen shot 2014-02-09 at 10 39 26 pm](https://f.cloud.github.com/assets/1800798/2175136/042beede-95ba-11e3-99fe-c15d5c47185f.png)

Although both frames are sent in a tight loop, the client machine waits for an ACK before sending the payload. This suggests that Bunny isn't disabling Nagle's algorithm as a read through implies it ought to. After some poking, I discovered the bug:

```ruby
     ::Socket.constants.include?(:TCP_NODELAY)  # => true
Bunny::Socket.constants.include?(:TCP_NODELAY)  # => false
```

By monkey-patching the implementation, I was able to achieve the desired result:

![statsd airbnb](https://f.cloud.github.com/assets/1800798/2175168/ac09c4dc-95ba-11e3-93d9-a28fb25a8327.png)