Certificate comments

This adds comments to the certificate page.

This depends on #623 - once that has been merged, the changes here will be a lot smaller.

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![screen shot 2013-10-10 at 16 15 22](https://f.cloud.github.com/assets/51385/1307396/de1a9b32-31be-11e3-9e1f-abae2d1c5369.png)