Add ability to log request ID to all output messages

[leplatrem]

Unlike dictConfig(), Python fileConfig() does not load filters from ini files

Therefore we cannot do the following from our config file:

+[filters]
+keys = request_id
+
+[filter_request_id]
+class = dockerflow.logging.RequestIdLogFilter

 [handler_consoler]
 class = StreamHandler
 args = (sys.stderr,)
 level = NOTSET
 formatter = json
+filters = (request_id,)

We have to do it via code. This PR provides a default stream handler that will add the filter for us.

The config will have to be changed like this though:

 [handler_consoler]
-class = StreamHandler
+class = kinto.core.StreamHandlerWithRequestID

Ref mozilla/remote-settings#777

Note

We could have done it in mozilla/remote-settings#778 but makes more sense in kinto.core since we already have kinto.core.JSONFormatter