refs #1 Generate scaffold of Items.
refs #1 Remove unnecessary files generated by scaffold.
refs #1 Rename table name 'items' to 'expenses'.
refs #1 Rename column name 'price' to 'amount'.
refs #1 Add index to expenses for category_id
refs #1 Remove unnecessary codes generated by scaffold.
refs #1 Modify tests to correspond with renamed table
refs #1 Change colmun of expenses amount not to be null
refs #1 Add validation for expense amount.
refs #1 Delete duplicated attributes.
Merge pull request #12 from upinetree/1_crud_expenses

1 crud expenses