Fix issue where shipping calculators were being passed objects other than Spree::Stock::Package

Fixes #3381
delegate cents to money for Spree::Money objects

Prevents ugly things like line_item.money.money.cents, which would just be line_item.money.cents with this change
[api] Remove address+delivery routes from orders

Fixes #3380
Track cost_price for variants on LineItems too

Fixes #3391
Correct CHANGELOG entry regarding ActiveRecord::Base.include_root_in_json

Originally entered here: https://github.com/spree/spree/commit/e1a1d7a
Removed an extra space in the admin Products tab list.

Fixes #3399
[API] Allow for extra parameters to be passed through to a line item

Fixes #3404
[frontend] stub generate_spree_api_key! for user stub in products con spec
[frontend] correct promo discount rate due to changes in 6ff655269916607f00feef75dbdbfd8fa482f83c