Change default logging to separate out WARN vs INFO levels.

[erikjohnston]

The idea is that we should store some INFO logs, but only keep a short period to allow for debugging without taking up too much room.

(Alternatively, we might want to document it in the default logging config so that it's easy to enable without completely turning everything off?)

[richvdh]

@ptman I notice that you have 👍 this: I assume you are aware this is something you can configure on a local instance if you so choose?

[ptman]

yes, I'm mostly just logging WARN currently