Add recipes for running the caa-indexer

Adding caa-indexer recipe …

The caa-indexer::default recipe installs the caa-indexer and all
dependencies on a machine, and runs it using daemontools.

The caa-indexer::rabbitmq recipe should be used on a machine
running RabbitMQ, and will create the necessary accounts and virtual
host for the caa-indexer to work.