Removed comment functionality.

Removed comment functionality.
It was coded a long time ago, and is just... too ugly.

    application/controllers/articles.php
    application/models/article_model.php
    application/views/pages/articles.php
Improved controllers, added keyword pruning

Improved controllers, and added keyword pruning.
    application/config/config.php
    application/config/routes.php
    application/controllers/articles.php -> application/controllers/article.php
    application/controllers/pages.php
    application/views/feed.php
    application/views/pages/articles.php
    css/style.css