This is to add the support on adding a 'cert' and a 'key', regarding a self-hosted Broker that requires a 'cert' and a 'key'. This will make the availability to call the 'Pact::VerificationTask' adding the 'cert' and 'key' to interact with the Self-Hosted Broker. As an example: --cert /path/to/client/cert.pem --key /path/to/client/key.pem