Grading interface should show name of Avenger

[martin-henz]

Currently any Instructor needs to look up the student in IVLE in order to find the Avenger who has done the grading. (This is for QA of grading.)

[remo5000]

@indocomsoft Is this something that can be passed in the request? I can definitely add it in. There's going to be issues though, such as what happens where multiple people grade a submission

[jiachen247]

#426 should resolve this issue. Students can now see the name of the avenger who last graded their submission.