Implement clone stage

### TODO

- [x] Add tests

### SCREENSHOT

![samson](https://cloud.githubusercontent.com/assets/1329716/3078462/8ad1f8d6-e473-11e3-8bbc-aaf9fac0851b.png)

Updated with ![new color](https://cloud.githubusercontent.com/assets/1329716/3087098/f843c578-e54c-11e3-9f57-296447c79c98.png)

/cc @zendesk/samson