[#007][ViviHuang&EasonLiu][add PromotionItem spec]
Merge remote-tracking branch 'refs/remotes/origin/master'

mmit.
[#007][ViviHuang&EasonLiu][realize add promotion item barcode into table promotion_items]
[#007][ViviHuang&EasonLiu][promotionItems table v2.0 not perfect]
[#007][ViviHuang&EasonLiu][save and del at table PromotionItem]
Merge branch 'master' of github.com:tw-preschool/letusgo-team-b