added checkout functionality to db + some cleanup
-rw-r--r-- 1429 TODO
-rw-r--r-- 5448 book_data.py
-rw-r--r-- 17189 browser.py
-rw-r--r-- 10386 db_layer.py
-rw-r--r-- 441 exceptions.py
-rw-r--r-- 9734 form.py
-rw-r--r-- 1999 help_bar.py
-rwxr-xr-x 3582 librarian.py
drwxr-xr-x - librarian_tests
drwxr-xr-x - ncurses_tools
-rw-r--r-- 1024 permissions.py
-rwxr-xr-x 224 run_tests.sh