Added storage of student data externally as a json object.

I didn't do this as a CSV file since some of the data columns would have multiple values (homework has four values, etc.), storing the data as a CSV would be messy, even though probably doable.

A cleaner way to store the data is as a json object.  Storing python data as json just requires importing the json module.  Data can then be loaded by opening and closing files with .open() and .close(), and by converting data with json.dump() and json.load().