1. Added a db constraint to enforce one submission from one student to  an assignment.

2. Add User implemented; modified RegisterController to set primary role properly.

3. Import G0 Students implemented. Other user imports can be added later by specifying different import types.

4. View, Add, Edit, and Search Student Standings implemented.

5. Email users in the search user results.

6. View, Add, Edit Advisement implemented.

7. Reorganized top menu.