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.