Job retries

```javascript
queue.enqueue(
  'retry', 
  { test: 'data' }, 
  { 
    retries: 2, //Pass in the number of times you want the job to be retried
    retryDelayMS: 50 // (Optional) Pass in the number of milliseconds to wait before retrying.
  }, 
  done
);
```

You can also pass a function to retryDelayMS, if you wanted to implement something like exponential backoff.