Make homepage more like a blog.

- Move welcome static page content to index.html template
- Include latest article in index
- Include up to 9 more article links underneath that
- And if there are 10 or more articles available, show a link to the
  Pelican builtin archives page with all articles on it.

Preview:
![screenshot from 2014-01-06 23 49 23](https://f.cloud.github.com/assets/1009019/1855151/861a80b4-7728-11e3-9a81-0a7ce7106c66.png)
![screenshot from 2014-01-06 23 49 28](https://f.cloud.github.com/assets/1009019/1855156/89968c7e-7728-11e3-9af0-80ce26b77191.png)