KAZOO-1413: quick ticky/formatting updates
KAZOO-1413: more formatting/tickies
KAZOO-1413: add ability to query API for system-wide registration counts

/v1/registrations/count - requires client to be superduper admin
KAZOO-1413: updating formatting
KAZOO-1413: add support to query registration counts only
KAZOO-1413: add AMQP fields for count-only queries
KAZOO-1413: clean up wh_json:foldl to strip undefined values from the json object
KAZOO-1413: remove from system_admin_mods and return data as json to be consistant with other APIs