Improve guardian style

 * Use a navigation bar very similar to the next gen web one reusing same colors and fonts
 * Update launchpage to use guardian font for the `g`
 * Update documentation links to be similar to next gen web links
 * Update labels (`Explore`, `Documentation`) and documentation style following Cantlin feedback

![screen shot 2014-07-24 at 19 00 42](https://cloud.githubusercontent.com/assets/615085/3692447/912a1d86-135c-11e4-9339-50255832b5b2.png)
![screen shot 2014-07-24 at 18 50 47](https://cloud.githubusercontent.com/assets/615085/3692382/1fe04ae2-135c-11e4-9338-fc86d305bc01.png)
![screen shot 2014-07-24 at 18 50 57](https://cloud.githubusercontent.com/assets/615085/3692383/1fe08f3e-135c-11e4-8aaf-689943072920.png)
![screen shot 2014-07-24 at 18 50 31](https://cloud.githubusercontent.com/assets/615085/3692387/26a11fb4-135c-11e4-93f5-0ba37b61fbcc.png)
![screen shot 2014-07-24 at 18 51 24](https://cloud.githubusercontent.com/assets/615085/3692399/3fe95e14-135c-11e4-9440-9e1cb630efe3.png)

Please note that you if you want to display guardian fonts locally, you will need an entry to your hosts file with a guardian subdomain pointing to localhost.