The order deadline is stored in UTC but we were comparing it to the
local timezone to decide if we need to close it.

* Closes: #27

Cents should be negative as well.

* Closes: #17

* Closes: #22

* Closes: #19

* Closes: #23

* Closes: #20

As we are changing the list of products

So we can modify expired orders

* Closes: #16