def perform
      if can_perform?
        response = HTTPI.post(uri, params_string)
        responder.from_json(response.body)
      else
        fail Bitkassa::Exception,
             "Your merchant_id or merchant_key are not set"
      end
    end
def perform
      if can_perform?
        response = HTTPI.post(uri, params_string)
        responder.from_json(response.body)
      else
        fail Bitkassa::Exception,
             "Your merchant_id or merchant_key are not set"
      end
    end
Initalize a request
 * +attributes+ +Hash+

 Make the request.

 returns +Bitkassa::PaymentResponse+ Regardless of the response, this
 this PaymentResponse is initialized.

 When a payment cannot be made because of incorrect or missing data,
 a +Bitkassa::Exception+ is raised.