Lifetime Value Calc
1. Introduce fields in Subs to capture the Lifetime value of a Sub, Similar to point 2.
2. Use frequency, value, cycle for lifetime Products.
3. Use frequency, value, cycle for lifetime Subs, copy from products.
4. Allow user to update this in change mode for lifetime subs.
5. add this field for Product CSV import and also Subs user import/Export fields.
6. Update all existing customer subs with defaults from product table.