Create a new service object with a configuration object

@param config [map] a map of configuration options
function Service(config) {
    if (!this.loadServiceClass) {
      throw AWS.util.error(new Error(),
        'Service must be constructed with `new\' operator');
    }
    var ServiceClass = this.loadServiceClass(config || {});
    if (ServiceClass) return new ServiceClass(config);
    this.initialize(config);
  }