Need the ability to delete budgets and items.

[shafeen]

Right now we can only create budgets and add items, but we can't delete an entire budget or remove an item that was added to a budget.

We need to be able to:

• [ ] permanently delete an item from a budget
• [ ] "soft" delete an item from a budget (tag it as removed without actually deleting its data)
• [ ] permanently delete an entire budget and all of its items
• [ ] "soft" delete a budget (tag it and its items as removed without actually deleting their data)

The "soft" deletes are important since we might want to be able to undo/restore a deleted item.