Environment variable overrides for ConfigList do not parse

[neko-kai]

Array overrides with environment variables, such as:

-Dsettings.list.0.elem="value"

Do not get parsed properly by circe config, this produces an error:

  C[A]: DownField(list)

Internally this structure gets printed as:

{"list":{"0":{"elem":"value"}}}

So it probably gets converted to an object with "0" as a key, not to a JsonArray. This would need either smart detection of objects with numeric keys or some kind of delaying of Json conversion as discussed here: #12 (comment)

See description of the syntax: lightbend/config#86 (comment)