MOD-56: Authentication and Authorization UI

The result of a lot work. Key components include:

- AuthCtrl and AuthService, which handle interacting with the login system and managing login state, respectively.
- AuthSuccessEndpointCtrl and auth-success.html, a popup window that receives the "success" callback from an OAuth provider, extracts the token, and passes it to AuthService.
- Login button and dropdown in application nav.
- A switch to ui-router instead of ng-route, which occurred because it was proving impossible to restrict access to protected resources using ng-route (and because the internet tells me ui-router is better for large projects)
- Unit tests for the controllers and services in this code