Update seeds to setup every lesson type.

@broccolini you can merge this PR and it will merge it into your new-design branch.

You can now run `script/bootstrap` at any time to get a fresh set of data, including 1 past lesson and 2 future lessons.

```
$ script/bootstrap
```

The two future lessons are neat because one has registration open and the other one's registration hasn't opened yet, but includes the form to get notified when the registration opens.

### Upcoming event with registration open

![coderdojo - san francisco](https://f.cloud.github.com/assets/623/1459667/e93adc2e-43ee-11e3-8e26-51efa9d6a998.jpg)

### Upcoming event with notify form

![coderdojo - san francisco-1](https://f.cloud.github.com/assets/623/1459674/0cc738c2-43ef-11e3-9283-a59e66ce172d.jpg)