0.3.6: fix giftcard promo

apply the amount only once per purchase, not once per store purchase.
The amount is split between store purchases

Add is_expired method

0.3.5

add test for is_expired

0.3.4

Performance optimisation

make update_items() more resilient

Update update_purchase

Make it more resilient so if there is bad data there it will update
purchase_items properly

0.3.2

Fix Model_PromotionTest::test_build_purchase_item()

0.3.1

Set is_payable and is_default to TRUE for promotions items by default

0.3.0: Use single-table inheritance for purchase items.

Make the promotions package compatible with openbuildings/purchases:0.5
Model_Purchase_Item_Promotion is replacing the "promotion" type

0.2.6

Update dependancies

0.2.5

Update dependencies.

0.2.4

add "not_promotion" filter