Otter Grade: Write out Individual Results as well as final_grades.csv

[sean-morris]

Is your feature request related to a problem? Please describe.
Currently, to understand what might have gone wrong in a notebook that has points taken off according to the final_grades.csv, you need to turn around and run otter run on that notebook. This is a problem for instructors using the service we provide.

Describe the solution you'd like
I would like the default behavior to be that we write the GradingResults objects summary field to a file whose name matches the notebook name. otter grade would then return a final_grades.csv and a folder of files each with their respective notebooks grading results.

Describe alternatives you've considered
This could be done via a plugin but first, we would need a new plugin event supported that occurs post-otter grade. The current events are tied to otter run. I am not quite sure the plugin is worth it; it is hard to believe that someone running otter grade would not want to see the individual notebook results.

Additional context
Also, I run otter grade in the context of a web application returning the results to the instructor. They are not running otter grade themselves(nor otter run for that matter) in most cases.

[sean-morris]

@chrispyles when you get a chance. I have a non-plugin solution ready -- it is pretty easy but not sure you want this behavior in the main distribution.

[chrispyles]

@sean-morris I'm fine with having this be part of the main package -- it sounds very useful -- but I'd like to put it behind a flag rather than having it be the default behavior (I don't want us generating several potentially unnecessary files in the user's system unless they ask for it).