created and last_modified now use DateTime
cleaned up various confusing tests
Merge pull request #2 from SysPete/datetime

created and last_modified now use DateTime
Add prerequisite on DateTime.
Add Peter Mottram to contributors.
Merge branch 'master' into moo_cart

Conflicts:
	Makefile.PL
	lib/Interchange6/Cart.pm
	t/cart.t