Option to wait for the end of the request

[nt1m]

Simplify:

request.on('data', chunk => {
  json += String(chunk);
});
request.on('end', () => {

by introducing an option.

[jankeromnes]

Great idea! I agree that we should find a sensible way to refactor this request-reading boilerplate.

I'm not sure whether it's better to address this in Self API directly, or in the code using it (e.g. Janitor).