Updates the proto definition to add a preview description and date
field. Date and description metadata from fetched content will be sent
over the wire. We can't render it locally yet, but at least this will
allow supporting recipients to display the content.
Also, made some minor changes to HTMLMetadata to better handle article
publish/modified date tags.
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.
