Get current issued books and all issued books by a user
Remove the non null contraint on returned on in user_books table
Refactor book index page to show checkout button and issue history
Refactor checkout controller for multiple books
Make fixtures for the user_book join table
Refactor checkin controller to account for user_books table
WIP to be squashed
Refactor the code to remove issued book records for a user
New helper methods for book to get issued books
Helper methods for user class to get the books issued by a user
Use transactional examples for tests
Refactor code to get issued books by a user
Remove non-null constraint on returned_on in db/schema
Refactor code to show user who have currently issued the book
Refactor user profile show code to show current issued books
Refactor feature spec to account for refactored fixtures