Fix submit.py with NetASM assignment so that testing is more robust

[feamster]

Things pass without proper completion of the assignment.

[wenhuizhang]

Hi, Professor and TA, I have already submitted NetASM HW, and it passed on that day. How could I know if I did complete the assignment or not please? P.S. while performing vagrant provisioning for the next assignment, I lost the original file on VM without saving them back to the repository. Is there anyway to see our submitted code?

Thank you so much !

Wenhui