template/base.html - Remove DNS prefetch for Google Fonts API

No longer use fonts from the Google Fonts API.
template/base.html - add Dublin Core metadata

Use Dublin Core metadata to mark up licensing (Creative Commons)
and authorship. Hopefully this will show up on Google searches
and expose Mindgames more to people looking for CC content.
template/base.html - add Creative Commons license to footer

This is how the original Mindgames page and content are licensed.