code: function App(root, options) {
    options = options || {};
    if (!root || typeof root !== 'string') {
      throw new Error('Application root is not provided or not a string.');
    }
    if (typeof options !== 'object') {
      throw new Error('Application options is not provided or not an object.');
    }
  
    Broadway.call(this, options, express());
    App.bootstrap(this, root);
  }
docs: Constructor function for the Slay app object.
  @param {string} root Root directory of the application
  @param {object} options Options for this app instance.
  @constructor