Maybe "status" instead of "active" or "public"

[gsf]

Since the query string query in elasticsearch doesn't handle booleans well (only with the ugly missing and exists syntax) and in order to facilitate potential multi-step publishing workflows, let's move from "active" or "public" booleans to a "status" field with "public" and "private" options. Possible options we could later add include "removed", "in-progress", "draft", and "disabled".