Fix title and link display, and calendar bug

Various fixes:

- calendar was broken!?
- darken the color of links making them more readable
- improve titre (h2 to h4)
- add assets version on config.yml to force refresh user cache
- compile CSS with ` -s compressed` option to win some bytes

![image](https://f.cloud.github.com/assets/225704/1692140/5782f4ca-5e73-11e3-94d3-41968976cb64.png)

=>

![image](https://f.cloud.github.com/assets/225704/1692144/6339e83c-5e73-11e3-8f91-3b0dbad66f55.png)

---
![image](https://f.cloud.github.com/assets/225704/1692146/78ffdaf0-5e73-11e3-9c0d-b0ed76f6d164.png)

=>

![image](https://f.cloud.github.com/assets/225704/1692145/709663ac-5e73-11e3-8871-88717a78e64e.png)