API changes for Yaocho.

These changes simply things on Yaocho a lot.

This would represent breaking changes in the API, so maybe I should change the API version, but I don't think this API is stable yet, so I don' think we need to bump the version.

r?
DRF is a lot happier with querysets, and this is used in DRF views. I don't like implementing the same logic twice, but they are different in important ways. Luckily this doesn't get called much by yaocho, so hopefully not hitting ES won't be a problem.