@NonNull
    public static Completable completeWithSuccess(final Single<Response> response) {
        return Completable.fromSingle(response.flatMap(withSuccess));
    }
Wait until a request has completed and check its response status. An exception will be thrown if the
request does not complete successfully.success status.

@param response the response to check
main/src/main/java/cgeo/geocaching/network/Network.java