Code Review + Staff Dashboard

This is a basic implementation of Code Review & Staff Dashboard. It accomplishes all of our goals for code review but there are certainly more things that are nice to haves. 

This may need some schema changes to migrate. 

![image](https://cloud.githubusercontent.com/assets/882381/4719064/af18bec8-5926-11e4-897b-7359b6f86f71.png)

![image](https://cloud.githubusercontent.com/assets/882381/4719137/47799bb0-5927-11e4-9f1e-9a0e5f6d9ccc.png)

![image](https://cloud.githubusercontent.com/assets/882381/4719160/620c37b2-5927-11e4-8822-94ee05023cce.png)

Student View:
![image](https://cloud.githubusercontent.com/assets/882381/4719105/0804f876-5927-11e4-84fa-e4c64e5a788e.png)

![image](https://cloud.githubusercontent.com/assets/882381/4719115/1d1c6758-5927-11e4-9542-852fb4c14496.png)

Nope - but I would love to have it be implemented so that the front-end can display submission. It would ideally return submissions that are graded - but I'm not sure where/how to best implement it.