Initial support for RSS Feed Reading

* Added an RSS feed reader to read MailChimp's RSS feed for newsletters
and to extract:
- Title
- Url
- PublishDate (DateTimeOffset)
- Plaintext summary of newsletter
* Added a UI item to test getting the latest newsletter content, and
writing it to the UI log.
* Re-enabled the UI log, because there was a bug where the scrollbar
wasn't working.  Instead of disabling the element, I should have instead
set readonly to true.
* Added a new configuration item, NewsletterFeed