NOJIRA : Fix header links to be white in default theme. 

Also modified header to be a link to home.

## Before

![image](https://cloud.githubusercontent.com/assets/3534544/2822915/ae1529fa-cf18-11e3-94a4-be7756a25e5d.png)

## After

![image](https://cloud.githubusercontent.com/assets/3534544/2822898/99dc7e84-cf18-11e3-9b81-49a4f8007560.png)