Sanitise Stripe API keys before using
See: https://civicrm.stackexchange.com/questions/28528/why-does-stripe-5-2-extension-hang-on-payment
We should pass the Stripe API keys through trim() or similar before using them, per https://github.com/mattwire/org.civicrm.smartdebit/blob/master/CRM/Core/Payment/Smartdebit.php#L632
Should probably swap them over so they are the right way around in the CiviCRM UI as well.