bug 1392457: Only return data needed for display
bug 1392457: Only return data needed for display

The Document model has gained several pre-processed fields over the
years. Rather than a blacklist, use a whitelist of the fields needed by
the views that call this method (sitemaps, filtered lists of documents).

SphinxKnight/kuma,Elchi3/kuma,a2sheppy/kuma,SphinxKnight/kuma,jwhitlock/kuma,mozilla/kuma,a2sheppy/kuma,jwhitlock/kuma,a2sheppy/kuma,escattone/kuma,mozilla/kuma,Elchi3/kuma,SphinxKnight/kuma,SphinxKnight/kuma,a2sheppy/kuma,SphinxKnight/kuma,Elchi3/kuma,jwhitlock/kuma,escattone/kuma,mozilla/kuma,jwhitlock/kuma,mozilla/kuma,SphinxKnight/kuma,Elchi3/kuma,Elchi3/kuma,jwhitlock/kuma,a2sheppy/kuma,escattone/kuma,mozilla/kuma