Change the Ship, Cart to do exception handling when calling a shipping driver,
as that's the message passing interface between the modules.
Add a noFormProcess field property that is recognized by processPropertiesFromFormPost.
Add more POD to FlatRate.pm, for the to be written calculate method.
Build create and new methods for Ship, convert existing code to throw exceptions.
Tests for Ship, that look suspiciously similar to ShipDriver.
