Correct feed-folder list, solve datetime keyerror and update beautifulsoup


* Correct feed-folder.html so it lists feed item's summary, not the body.

* Solve datetime KeyError: u'+0000. due to GMT not especified (see second error in issue #7). Test example: http://planet.python.org/rss20.xml always has <pubDate>Thu, 14 Nov 2013 22:57:42 +0000</pubDate>. The error appears when you restart your instance.

* Update to beautifulsoup4 and use python's built-in HTML parser (solved errors I hit when the feed had some escape characters in it, but unable to reproduce).