showLog should stream response

[gsf]

The code block below shows that showLog in client.js buffers the response received when we hit the log endpoint (from line 191 of client.js):

api.get(logUrl, function(err, req, res, result) {
  if (err) return callback(err);
  callback(null, res.body); // This is weird that result is empty and res.body isn't
});

By comparison, a simple curl localhost:8888/log returns an immediate, streaming response. The showLog method should do the same.

This could be the beginning of a larger refactor away from restify, since we have to drop down to its ugly HttpClient, at which point I'd rather just use request or even http.request.