This branch makes improvements to how HTML metadata is parsed. Now,
we'll parse other kinds of opengraph tags as well as title, favicon, and
meta description.
This branch also modifies how URL validation is performed. Before,
international URLs were not supported due to NSURL/NSDataDetectors
handling of punycode. Now, there are mechanisms to detect non-ASCII URLs
that have been parsed and validate that they are comprised of the
correct characters.
