New lib: deferred-queue

Hi,

Some months ago I made a control flow lib aimed to be the glue between sync-style api calls and pure async modules. It's very similar to async.waterfall but it is 2,6 times faster and allows you to pause/resume the queue at any time. The error handling and the pass of the parameters through the tasks are a bit different.

```bash
$ node performance.js --n 10000 --t 1 --file ./examples/callbacks-deferred-queue.js
{"time":299,"mem":56.9296875,"errors":0,"lastErr":null}

$ node performance.js --n 10000 --t 1 --file ./examples/callbacks-async-waterfall
{"time":813,"mem":59.12109375,"errors":0,"lastErr":null}
```