refs #101 'add a function that create, update and delete the records'
refs #101 'create a function that create, update and delete the records'
refs #103 'add a background image'
refs #102 'add the barance of payments about the categories'
refs #102 'add the model specs about the barance of payments'
refs #104 'add the dependent destroy about category'
refs #105 'display the records that group by each month'
refs #105 'add controller spec about the records'