Stub out lib/quench and Redis backend

This commit stubs out the basic patterns for queues and queue
methods. Creating a new queue and adding a new item to it will
play out something like this:

```js
var widgetQueue = require('quench')({backend: 'redis'});
widgetQueue.add('my first widget', {
  color: 'red',
  size: 'large'
}, callback);
```