add Shuffle keyword that allows a batch to be created from multiple files

[benfred]

Issue by jperez999 Tuesday Jan 28, 2020 at 05:39 GMT Originally opened as https://github.com/rapidsai/recsys/issues/14

---

Is your feature request related to a problem? Please describe. Need to ensure that no two batches are ever the same, even when doing multiple epochs

Describe the solution you'd like A keyword, shuffle. The argument will trigger the shuffle.