Adding a RabbitMQFirehoseFactory implementation

Pretty self explanatory.

The major things to be aware of:

1) This implementation will not reconnect if the connection to the MQ broker is lost. This is documented in the JavaDoc class documentation.

2) I added a rabbitmq directory to the examples/bin directory. However, it only contains an example realtime.spec configuration file to get a realtime node running with the RabbitMQFirehoseFactory and a simple example query.body file. It doesn't contain a client that actually produces data into the RabbitMQ exchange. I can provide a simple Java program that does this but I wasn't sure where I should put it.

3) There are some configuration options that are missing. We know about this and we may add it later on. Specifically, neither SASL nor SSL is currently supported.