Added simple feed with latest posts.

Added simple RSS feed which serves latest posts, linked in footer.
![screenshot 2014-11-05 10 29 43](https://cloud.githubusercontent.com/assets/727413/4915387/a3bc8484-64ce-11e4-80e4-5b00d6b484e3.png)

I think we need header content type xml.  I mean it may not be strictly required but we should add it I think.