Add reviews

* add ability to review recipes
* write and edit reviews (no destroy yet)
* add simplecov for unit test coverage
* get close to 100% coverage

![Screen Shot 2013-02-27 at 11 31 58 PM](https://f.cloud.github.com/assets/705514/204441/0e1b9396-8179-11e2-8f02-e97639db5a74.png)
![Screen Shot 2013-02-27 at 11 32 17 PM](https://f.cloud.github.com/assets/705514/204442/11730664-8179-11e2-8cbf-d3cfdedad0b2.png)