Added support for SSL stapling of OCSP responses.

Example usage:
ssl_stapling => true,
ssl_stapling_verify => true,
ssl_trusted_cert => 'puppet:///modules/modulename/ssl.hostname.crt',
ssl_stapling_file => 'puppet:///modules/modulename/ssl.hostname.key',
ssl_stapling_responder => 'http://www.example1.com',
resolver => 'http://www.example2.com',