Fixes two bugs.
* I'd been handling Loggly search query parameters by just joining them together, which is wrong and dumb because the requests module does such a better job of it. Not escaping spaces was leading to weird behavior.
* The `message` member of a RequestError was trying to get a JSON-parsed version of the response body, but this is also wrong and dumb because if something's gone wrong with the request, we shouldn't assume the response is JSON-parsable.