Do not generate a new identifier for a payment when it is re-saved

Fixes #3733
remove unnecessary semicolon in screen.css.scss

Fixes #3729
[backend] Move 'Taxonomies' configuration out from under 'Configuration' to 'Products' subheading
[backend] Make checks for order totals more specific in specs

Probably fixes strange build failures like: http://ci.spreecommerce.com/viewLog.html?buildId=22440&buildTypeId=bt6&tab=buildLog
Product#stock_items should return stock_items for the master variant too

Fixes #3737
Add a default format if no format is defined in the locale file. Use the same default format as the datepicker gets in the translations partial.

Fixes #3602
While an order_id field exists within inventory_units, we should be able to retrieve these using an association

Fixes #3744
Add regression test for #3744
Associate user in Order `merge!` when possible

Users might be losing their cart changes when they come back but don't
visit either the /cart page or the /checkout

Fixes #3742
Fixes #3736
Bump active merchant to 1.38.1

Fixes #3745
refactored spree stock estimator

Extracted functionality out of #shipping_rates for choosing the default
shipping rate and the for the order shipping rates should be sorted in,
in the interest of overriding said behavior.

Change-Id: Iefcce00f1f2ebfedd565dd3aeb540a6111ffc5b7

Fixes #3748
Fix product paging issue

Fixes #2851
Fixes #3064

Conflicts:
	frontend/app/controllers/spree/taxons_controller.rb
Fix expectations in order/adjustments_spec so that it now passes
Assign location to shipment when importing orders (api) [Fixes #3775]
Should have ability to ensure confirm step is always in progress bar.
Update credit card factory to work any year.
Fix Order#confirmation_required? spec.
Use Time.now.year as Date.year is invalid.
fix page action buttons line wrap in admin