LightDM is the display manager used in Ubuntu.

Acceptance Criteria

1. Branch must compile
2. Regression tests must succeed (make check)
3. Able to log in with user that has a password (using Unity Greeter)
4. Able to log in with user that has no password
5. Able to log into guest session
6. Able to switch users
7. Able to log in user that is using encrypted home directories