Calls functions once a promise has been delivered.
var prom = require('prom');
var onready = prom();
onready(console.log.bind(console, 'one'));
onready(console.log.bind(console, 'two'));
// Deliver the promise
onready.deliver('delivered-arg-1', 'delivered-arg-2').
// > one delivered-arg-1 delivered-arg-2
// > two delivered-arg-1 delivered-arg-2
// Once the promise has been delivered, the callback on next event loop.
onready(console.log.bind(console, 'three'))
// > three delivered-arg-1 delivered-arg-2MIT