Fix consuming user credits upon completion.
Fix consuming user credits upon completion.

gogo52cn/spree_store_credits,developingchris/spree_store_credits,dotandbo/spree_store_credits,AgilTec/spree_store_credits,AgilTec/spree_store_credits,gogo52cn/spree_store_credits,spree-contrib/spree_store_credits,developingchris/spree_store_credits,AgilTec/spree_store_credits,spree-contrib/spree_store_credits,gogo52cn/spree_store_credits,dotandbo/spree_store_credits,developingchris/spree_store_credits