Allow the referrer (via the 'r' parameter) to be passed without signature failure.
Update GoCardless.php

Corrected type for GoCardless::$client.
Merge branch 'Crowdcube_master' of https://github.com/RQuadling/gocardless-php into Crowdcube_master

* 'Crowdcube_master' of https://github.com/RQuadling/gocardless-php:
  Update GoCardless.php
  Allow the referrer (via the 'r' parameter) to be passed without signature failure.