Csv export auth

Sorry this is from learningequality to learningequality. I think because of some trouble with the kalite-submodule (working from the central codebase) I set my origin to learningequality rather than my own fork and forgot about it. 

Summary: Adds 3 api endpoints (FacilityUser, TestLog, and AttemptLog), which allow filtering based on zone, facility, or group, and return the appropriate data serialized to CSV. Also includes a backbone app which serves as the front-end for the API. Pics below. 

From central server, admins can select combination of zone, facility, student group, and resource type (users, test, or attempts:

![selection_067](https://cloud.githubusercontent.com/assets/1319950/4172155/11550ebc-3545-11e4-8767-4d0c799a280e.png)

On distributed, same idea, minus the ability to select zone:
![selection_068](https://cloud.githubusercontent.com/assets/1319950/4172159/20a60a9c-3545-11e4-87fe-bed2d563a0fc.png)

Lingering issues:
* no tests yet (although works in manual testing) 
* currently returns a blank CSV when an admin picks a combination that returns 0 results. Eg if there are no students at a facility and they click export, it will be empty rather than returning an error message. Currently this is by design, but we could handle it better in future. 
* File names are currently just 'download' without an extension. I couldn't figure out how to do this easily, and I think it's ok for now, but something to flag for follow up 
* May need refactor, see my comments on Part 1 in central server codebase: https://github.com/fle-internal/ka-lite-central/pull/190

Might be good to clear/reset/disable the dropdown before fetching anyway, since if the fetch is slow, it could be showing them an outdated dropdown that will suddenly change even if they're partway through selecting something.