Refactored line_items_request to create_line_item_request
Added line_items attribute to the fetched order
Fixed a bug in LineItem#create_line_item
Changed how Order.fetch! invokes a given block
Spree.update_line_item and Spree.delete_line_item, check
Changed the update_line_item API call to put when no block is given
Fixed a typo in a method call
OrderModel#refresh retrieves the order from the endpoint
Merge pull request #5 from sergelerator/create_line_items

Spree.update_line_item and Spree.delete_line_item, check