KAZOO-543: formatting and remove logging
KAZOO-543: add clauses to rid ourselves of unnecessary logging
KAZOO-543: log current agents known by queue
KAZOO-543: add specs
KAZOO-543: match unused casts in gen_listeners
KAZOO-543: play error if device has multiple owners
KAZOO-543: start agent only in queue

if an agent is logged out, and uses the queue_login callflow, only log the agent
into that queue (even if they're configured for others).
KAZOO-543: if agent has no endpoints, log them out
KAZOO-543: add start_link with explicit list of queues to log into
KAZOO-543: update agent status on queue_login if not logged in in general