Futures v2.0 is just around the corner!

[AJ ONeal]

I'm looking for feedback on the API before I finalize it.

https://github.com/coolaj86/futures/tree/v2.0

The API is leaner, the code is leaner, and I've included Node.JS's EventEmitter (with minor modification so that it works in the browser).

Notable Changes

* all examples now use the function(err, data [, ...]) convention for callbacks.

* `promises` and `subscriptions` have been combined into a single `future` object.

* `whenever` replaces `subscribe`

* `join` absorbed `synchronize` and now uses`join.add()` to add futures

* `emitter` added from node.js

* `loop` replaces `whilst` and is easier to reason about.

AJ ONeal