Fix properties search icon and failing spec

Fixes a failing feature spec (Unable to find css ".fa-search")
introduced in 2e9002a36b24b22f120bf9494b51a0fec3eebf4c.

Using the correct icon for the search button fixes this.
Simplify records created form line_item factory

Instead of creating a variant, which creates a product and a master
variant (thus creating two variants), just use the product factory and
reference variant created.

This makes core specs run very slightly faster on my machine (a few
seconds off of ~1:30) and I think this is closer to what people would
expect create(:line_item) to do.

Fixes #4852
Drop nonsense api/checkouts#ip_address
fix permalink handling to force uniqueueness and rename on product destroy

Fixes #4805

Conflicts:
	core/spec/models/spree/product_spec.rb
'quantity -= amount' is the same as 'quantity += -amount'
Make migration more tolerant of deleted Variants

This migration bailed for me when it found an old order (before Spree used `acts_as_paranoid`) with a line_item referencing a Variant that no longer existed.

Making the migration use `variant_id` instead of `variant.id` fixed this problem for me, and I suspect will make the migration path smoother for other people who have been using Spree since before the `paranoia` gem.

Fixes #4822
Bump activemerchant to 1.43.1

This should fix spree/spree_gateway#149
Delegate accessor line_item.sku to variant

(Addressing conversation in https://github.com/spree/spree/pull/4856)

Fixes #4860
Don't assume default variant in JS. Let this be controlled by HTML markup.

Fixes #4849
Downcasing locale for jquery.validate i18n messages

Fixes #4867
add a new alias action :display and refactor some code of ability

Fixes #4865
Remove include of product filter on spree taxons

I don't know what these used to do, but they don't do that anymore.

Fixes #4861
Added initSelection to variant_autocomplete

Fixes #4862

Conflicts:
	backend/app/assets/javascripts/spree/backend/variant_autocomplete.js.erb
Don't load line items to calculate the amount, use the database to obtain the result
Fix prev next icons on datepicker

apply a .fa class so font-awesome icons work fine

Fixes #4876
fixes #4866 (wrong iso3 code for romania)

fixes #4875
fixes #4874
Fix pagination for taxons

Fixes #4873
Fixes #4854
Update shipment in proper chronological order

Every time the selected shipping rate has changed as a shipment cost
change should be propagated through order totals and states

About #4845
Add CHANGELOG entry for preference changes
Add changelog entry for multi-domain changes