Start a FAQ page

* Add a HighVoltage page at `/faq`

Minor:
* Move styles for anchor tags from `_base` into the more specific `_header` where it used

https://trello.com/c/h9zfaC9l/386-add-an-faq

![image](https://cloud.githubusercontent.com/assets/913757/4729268/98eab5d2-5982-11e4-8848-b144066c5b6b.png)