Created the initialize method for the library class
Added the books and list_books methods
current version from Friday
Updated list_books method
Added check_out method
added available_books method
added print_borrowed_books method
Added check in method and updated main to check the method
Debugged check-in method and fixed main.rb test of check-in method
Added getters and setters to borrower and book classes/removed superfluous code
Added comments to all methods in library.rb
Made minor comment modifications