Fixed some issues with tags in the page title
Disqus comments are shown by default if enabled
Slightly change layout of category and tags display
Sort authors and categories
Use *.slug instead of category/feed as latter includes relative URL.

The page_name variable includes relative path to the actual page_name
so it won't necessary match the feed file name if they are not in
the same path.

The category.slug and tag.slug variables instead are just a
shorthand for slugified category/tag name, which is what we need.