Write a notes autograder

[norcalbiostat]

Ultimate goal: create a function to read in a pdf and calculate a grade. Will be used to loop over multiple PDF's in a folder.
Use prior Math 130 notes auto-render script (in the autograder folder) as starter code.

Criteria to implement

• Before run, delete any pdf's that are also found in the entered folder
• If the error phrase Error in parse(text = input) shows up anywhere, set message to "fix YAML"
• read the student name from the file name
• check for the student name in the author section. Anything other than "Put your name here"
• create a data frame with student name and either a score or an error message
• score is % complete
• completion should be based on a key - which will be different for each assignment. Perhaps an argument in this function takes a key PDF and does some sort of diff check - but only on the code?