Log more autograding errors (#709)
Log more autograding errors (#709)

Integrating a few of cg2v's improvements:

* Log more autograding errors

Try to always send something to the course log when autograding
submission to tango fails or is incomplete

* Fix logging (flash is a string, not array)

autolab/Autolab,autolab/Autolab,cg2v/Autolab,cg2v/Autolab,cg2v/Autolab,autolab/Autolab,cg2v/Autolab,cg2v/Autolab,autolab/Autolab,autolab/Autolab,cg2v/Autolab,autolab/Autolab