until

__unitl__ is a very simple helper object that helps on waiting multiple
__EventEmitter__. It is an EventEmitter itselt, and it waits for all the
__EventEmitter__ firing success events, or one of them firing failure event.

The APIs are

var waitings = new require('until').Waitings();
waitings.add(EventEmitter e,
Array or String success events,
Array or String fail events,
Array or String notification events)

An example:

var waitings = new until.Waitings();
waitings.add(emitter, // The emitter object
['ok', 'done'], // A list of event names that stand for success.
['bad', 'fail'], // A list of event names that stand for failure.
['progress']); // A list of event names will continuously send.

Event: 'ok'

TODO

Event: 'error'

TODO

Event: 'notice'

TODO