Fix for no item.line_item method in 2-1-stable
Fix for no item.line_item method in 2-1-stable

The ContentItem quantity may be different to the line item quantity, too.

Fixes #2
Fixes #3

Bombsheller/spree_easypost,Bombsheller/spree_easypost,leggers/spree_easypost,njakic/spree_easypost,leggers/spree_easypost