Rabbitmq topic

I created a rabbitmq topic handler, which will take the data from diamond and send it to a rabbitmq exchange. This handler allows you to specify the RabbitMQ vhost, user, password, and exchange name. This is based on the zmq and rmqpubsub handlers.

Also by default the routing key is set to the metrics full path, but you can override it and specify and arbitrary routing_key to allow selective consumption of the metrics data.