Creating a checkout program that:
    * Reads a list of books from goodreads
    * Enables users to search for books from the list
    * Enables users to "checkout" a book, and record the checkout in an excel spreadsheet

User uses application for the first time:
    Checkout notices the empty persistence file and detects that this a new run
    Asks user to authenticate with goodreads
    Asks user which shelf contains all of the books available
    Asks user which shelf to use as the "checkedout" shelf.
    Asks user where to store the spreadsheet
    Goes into student mode

User wants to checkout a book:
    User searches the teacher's shelf for a book
    User checks if the book is available
    If the book is available then ask the student if they would like to check it out
    Add the book to the "checkedout" shelf
    Update the spreadsheet to indicate that the book has been checkedout

User returns a book:
    User searches the teacher's shelf for the book
    Marks the book as returned
    The spreadsheet is updated to indicate that the book has been returned