We may use a different port in the config that is then mapped somehow.
But this should not affect where we try to contact remote nicknym servers.

Dropped the webmock dependency. We have our own http adapter. So we can
stub that to inject a mock. As an added bonus this does not mess with
other http requests.

Also wrote down testing strategy. Not completely implemented yet.

Also changed Nickserver::Response to not include the status code.
This may be okay for error responses but in most cases we want to
have a parsable message and not some status code prepended to it.

I added a RequestHandler that uses Nicknym::Source - but that has not
been implemented yet.