Updated the in-code API docs, and added a new way to generate them

So basically, I talked with mick about the need for proper, complete API documentation some time ago, probably around the meetup. This has taken some time to complete, and there are probably some stuff  and options I have missed, so feel free to proof-read (see links below).

I looked at various options for generating documentation from comments, and settled with a combination of jsdocs comments + [dox](https://github.com/visionmedia/dox) and [markdox](https://github.com/cbou/markdox). I use a custom template to generate markdown code, which is then transferred to the wiki. 

There was some leftover code from saschas(?) attempt with YUIDocs, I've deleted all those. I looked at YUIDocs when trying to choose what library to use, but settled with markdox in the end because it seemed more lightweight.

I imagine the process of updating API docs like this:

1. API is changed
2. API doc is updated
    1. The person who changed the API also updates to docs - hooray!
    2. Jan updates the API docs - :(
3. Jan runs the `docs/markdox.js` script to regenerate the docs, and pushes the changes to the wiki (yes, the wiki can be cloned like a regular repo)

* https://github.com/sequelize/sequelize/wiki/API-Reference-BETA-DAOFactory
* https://github.com/sequelize/sequelize/wiki/API-Reference-BETA-DAO
* https://github.com/sequelize/sequelize/wiki/API-Reference-BETA-Sequelize
* https://github.com/sequelize/sequelize/wiki/API-Reference-BETA-Hooks
* https://github.com/sequelize/sequelize/wiki/API-Reference-BETA-Associations
* https://github.com/sequelize/sequelize/wiki/API-Reference-BETA-QueryChainer
* https://github.com/sequelize/sequelize/wiki/API-Reference-BETA-EventEmitter