Make log shipping more efficient and reliable

The beaver log shipping utility would emit lots of errors and get stuck very often when using rabbitmq as the intermediate for log shipping to logstash for parsing. Also, the logstash end of things would hang and require restart very often as well. This PR converts beaver (on all nodes) to use client-side zmq and logstash (only on head nodes) to use server-side zmq and get balanced across by the HAProxy bound to the VIP.