add docs/, and a way to generate docs

This branch adds documentation to `gh-pages`. It can be generated with the `generate-docs.sh` script, e.g. `./generate-docs.sh v0.23.2`. Here's a screenshot:

![screen shot 2014-08-08 at 11 53 37 am](https://cloud.githubusercontent.com/assets/3344958/3861267/5634f9c6-1f2d-11e4-8fad-1417a3a59ec2.png)

This isn't the best documentation in the world since it still contains private and "protected" field, but it's better than nothing.