Add delete method for expense class.
Add update methods for description, amount and date of expense class.
Fix rspec tests for update methods to accurately check if the database is being updated, as well as the instance variables in the expense object.
Add Category class with readable attributes for description and id.
Add read all, save, == and delete methods to category class. Make delete rspec test more accurate for both expense and category classes by testing to make sure it's in the database before deleting it and then testing to see if it has been removed.
Add update method for description to category class. Make update rspec tests more accurate for both expense and category classes so that they check the database value before and after the update.
In Expense class, create add_category method to join an expense with one or more categories and categories method to read back all the categories which the expense belongs to.
Refactor categories method in expense class to use a join. Also add line to clear the join table each time tests are run.
Add rest of main menu to ui and add methods for creating categories and listing all expenses and categories.
WIP add UI edit methods.