Fix rss issues

Change summary (thanks @chrisdoohan):

• Add a version="2.0" attribute to the <rss> tag, to allow validation of the feed.
• Swap date time format in the <pubDate> element from truncated ISO to RFC-822 (validators were flagging this).
• Add the QOL atom:link element in the <channel>, for compatibility with various readers. Validators flagged this as a potential issue. Apparently the attributes in that tag help identify the content source, if a feed item has been through aggregators and is being served in a different feed.
• Add tests
• Minor formatting changes to remove whitespace