Pass tests for Books class.
Change attribute accessor.
Pass initial tests for Bin and Ship classes.
Pass initial tests for Bin and Ship classes.
Organize files. All tests pass.
Pass test for multiple boxes.
Fix rounding quirk with floats.
App returns json object for boxes.
Refactor Ship command.
Refactor code and add extensions text file.
Refactor code and add extensions text file.
Fix test.