Fixes undefined method setAuth on REST module

After the replace of Goutte to Guzzle, I'm getting the `Fatal error: 
Call to undefined method Codeception\Lib\Connector\Guzzle::setAuth() in /vendor/codeception/codeception/src/Codeception/Module/REST.php on line 198`
Merge pull request #1022 from andersonamuller/patch-1

Fixes undefined method setAuth on REST module