Adding SEO tags, updating toc design

* Added a subtle border along the edge of the table of contents. 
* Added robots.txt to prevent duplicate indexing of freemarker docs and api
* Added canonical, prev, and next urls for better indexing

![image](https://cloud.githubusercontent.com/assets/993432/4784418/11ad0176-5d54-11e4-83cf-adb88053209f.png)