Partially obscure parameters in swagger and api

We can't totally obscure things and fairly call this an "open" api.
However, if we prefer to limit experimentation by novice developers,
it seems prudent to at least partially obscure some options in the
user-friendly Swagger for our api. This seemed especially important
for the data_host option, which could be susceptible to abuse. So,
all models/schemas are published via `ws/openapi.json`, but only
"default" options are displayed on the Swagger page's "Try it out"
section.