list all charges even if there isn't a due date

Allow parents to select any charge that is on their account when paying, regardless of it there is a due date or not.

Right now, the only charges parents can select are ones with due dates. However, DSP doesn't require us as SOs to add a due date to a charge. When we forget, it makes extra work for us with having to figure out which charge a parent's payment was attached to so we can unassign it and get it attached to the correct payment.

With this option, all charges would be options for the parent to select when paying so we don't have to go back through and figure things out later.

Conversely, if it is easier to have the system require us to set a due date for a charge to post, that would be fine too.