load pages class in index.php, before any output

Need to set http_response_code before any html is output.
Send a 404 if no $content (issue #26)

Several other checks in place thoughout as well.

If nothing was found for the request, throw a 404.
Basic template for error page (issue #26)

Will fill out more later. Just a basic template to see that it's
working.
Do not minify when setting
Apply article style to [data-error] too
More work on error pages

Set title, description, keywords.

Slightly modified error page template includes img, link back
home, an error message, and a dump of url_parse()
More character...