KAZOO-1039: add compact logging, and expose format_error so others can use it
KAZOO-866: maintenance functions to check subs and presence state
KAZOO-866: add guards to add_binding/2
KAZOO-866: add call_custom function to allow worker to bind to alternative direct exchange
KAZOO-866: expose the call_custom worker function through whapps_util
KAZOO-866: clean up log lines
KAZOO-866: add ability to bind/unbind from the presence updates exchange
KAZOO-866: move Queue to option field for Subscribe payloads
KAZOO-866: find the response queue using the Queue or Server-ID field
KAZOO-866: handling of subscriptions, and sending inital presence state