Ensure consistency with latest mongodb nosql spec

[balupton]

Mongo NoSQL Spec: https://docs.mongodb.org/manual/reference/operator/query/

Any query-engine specific selectors should either be removed, or prefixed with $qe

The current $in should be changed to mongo spec'd $in and a new $qeContains, or the like

There should also be a $qeWithin.

Details: https://bevry.slack.com/archives/maintenance/p1456474718000276

@blitmap is in charge for this