[Test Case] Instructor submit, annotate assignment, and release grades

[victorhuangwq]

Adds a new selenium test case that:

1. Act a student and make a submission
2. Return back to being an instructor
3. Create an annotation, with a grade added to it
4. Set grading deadline to be present
5. Release grades
6. Act a student and see if they can see the grades, annotation (on both the autograding feedback page and the speedgrader page)