Add check for plugins similar to module checks?

[jschmi01]

I've added some code to do similar checking for plugin

elseif ($input->get('plugin'))
{
    $plugin = $input->get('plugin');
    if (JPluginHelper::importPlugin('ajax', $plugin))
    {
        $dispatcher = JEventDispatcher::getInstance();
        $plugin = ucfirst($plugin);
        
        try
        {
            $results = $dispatcher->trigger('onAjax' . $plugin);
        }
        catch (Exception $e)
        {
            $results = $e;
        }
    }
    else
        $results = new LogicException(JText::sprintf('COM_AJAX_PLUGIN_NOT_ACCESSIBLE', $plugin), 404);
}