[PRE-RELEASE-0.4] Create utilities to avoid using the `predict_id` in queries

[blythed]

trafficstars

1. db['_outputs__<identifier>__<uuid>'] should work even if user gives db['_outputs__<identifier>'].
2. db['docs'].select().outputs("<identifier>__<uuid>") should work as db['docs'].select().outputs("<identifier>")

The expected behaviour is that the latest version should be loaded.

TODO: check that these are the only places needed.