update DRF to 3.x

Need @jsatt to take a look at this and spot-check DRF api requests via the API site. I went thru as much as I can, so a quick spot-check of create, retrieve, update, and delete of bids should be enough.
[apparently `queryset` is the new hotness](https://github.com/tomchristie/django-rest-framework/issues/2366).