new sections to be added

[Matt Aimonetti]

Hi  everyone,

 I hope you all enjoyed some time off and recovered from the Merb/Rails announcement :)  Before I forget, Happy "whateveryoucelebrate".

This week I want to focus on the book and we need to make some major modifications:

- add a section on Sequel written by Lori and Jacob from YP
- add a new section on ActiveRecord
- Add a future section on migrations to the next release

Because of these major modifications, I would like everyone to push their modifications and to send me their pull requests.

Thanks,

- Matt