Replaced some unnecessary Octopress filters.
Moved sidebar into the default template.
Moved article header into post/header.html.
Broke up article.html.
Use post/header.html for pages, too.
Moved post footer into post/footer.html.
Use post/header.html for pages, too.
Deleted unused category_feed.xml.
Simplified RSS XML and removed unnecessary filters.
Removed custom includes.