override rails_ujs confirm with bootbox.confirm

confirm.js

  $.rails.allowAction = function(element) {
    var message = element.data('confirm');
    if (!message) {
      return true;
    }

    bootbox.confirm(message, function(result) {
      if (result) {
        $.rails.handleMethod(element);
      }
    });

    return false;
  };