template/metadata: make category optional
template auto-detects banner for article

simply place "_banner.jpg" in the article directory.

Updated "Making Time For Quality" to match
style: make small type bigger
article/template,style: wide footer, further reads

currently the wide footer depends on the presence of
"_further_reading.markdown" in the article's directory.
style: misc improvements
template/article: misc improvements

instead of article.metadata.lead_text, the template auto-pulls from
_intro.markdown in the article directory.

allows for metadata content into the style attributes of the article header
title and subtitle.  These don't need classes generally.
article: refining software