Get remote data

This pull request enables getting questions and answers from ES.

The ES parent-child mapping API is extremely disgusting. You cannot access a child directly without knowing its parents' id. Instead, I search for any answer matching the id of the child, which kind of defeats the purpose of this whole mapping mess. (At least it's a reasonable setup for getting all children at once.)

At least it seems to work.

(RemoteDataStore is still disabled via the DataManager)