Github style header anchors

Github style header anchors.  Uses the octicons https://octicons.github.com/ but stripped down to just the character we need to keep size reasonable.

![screenshot 2014-07-03 22 35 38](https://cloud.githubusercontent.com/assets/1055125/3478315/f9d8fcae-0334-11e4-8b4a-672556491d04.png)