Update to PubSubHubbub Core 0.3 Working Draft

[jmonteiro]

The PubSubHubbub Core 0.3 working draft (http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.3.html) got some interesting features. Guess I can try to make webglue compatible with it :)

[zh]

Fill free to work on it. I'm not sure when will have time to work on improvements.