Integrate third party library like unirest.io/php.html

Figured this out through experimentation

1) Download the Unirest repo.
2) Copy its src folder into your application/libraries, resulting in Unirest.php and the Unirest folder there.
3) Modify application/libraries/Unirest.php, adding a bogus class to make CI happy

Code:

<?php

require_once dirname(__FILE__) . '/Unirest/Exception.php';
require_once dirname(__FILE__) . '/Unirest/Method.php';
require_once dirname(__FILE__) . '/Unirest/Response.php';
require_once dirname(__FILE__) . '/Unirest/Request.php';
require_once dirname(__FILE__) . '/Unirest/Request/Body.php';

// bogus class to make CI happy
class Unirest {
}

4) You should now be able to use the conventional CI loader ... $this->load->library('unirest'); and then use the package per the Unirest docs