[backend] Use the controller name rather than Object when a model does not exist for authorize_admin method

Fixes #3622
Move preference_resuce.rb into Core, where it should've been

Fixes #3860
Fix issue where cancelling a line item delete didn't actually cancel it

Fixes #3862

Conflicts:
	backend/app/views/spree/admin/orders/_shipment_manifest.html.erb
Do-over "Add Stock Movement" form

If there are a large number of stock items for this stock location, the page can take some seconds to load, as mentioned in this thread:

https://groups.google.com/forum/#!topic/spree-user/nu0_NlNGPV8

To make that stop being a problem, I've switched that UI to using select2 to load stock items 50 at a time. I've also imporved the UI to show more information about the product, such as its SKU and its options text.
[backend] Include options text when displaying variants on the stock movements page
[api] Add eager loading for option values + option types to stock items

Conflicts:
	api/app/controllers/spree/api/stock_items_controller.rb
[api] include option_type presentation within option_value_attributes
[backend] More clearly differentiate select2 result elements
[backend] Split variants/_autocomplete into two templates which can be used independently
Bump to 2.0.6
Add release notes for 2.0.6
Bump to 2.0.7.beta
make sure we lock deface at version 0.9.1
Use more strict dependencies

Using ">= 1.0.0" is likely to give us trouble any time a dependency
releases a major version
Remove append_view_path from api ControllerSetup

That line was preventing us from overriding templates within other
application or extensions

Fixes #3450
Shipments need to check if they can get rates

before trying to get them, a private method
has been added to check if the shipment is ready
to get rates, currently it only checks if the order
has set a shipping_address, if theres custom business
logic for a specific store this is what they should
be customising instead of the refresh_rates call
which is already getting too complicated by itself.

Added tests for this and had to include a before call
to stub this same call in order for the other tests to pass.

fixes #3848
fixes #3849
Simplify `can_get_rates?` in Shipment
Revert "Remove append_view_path from api ControllerSetup"

This reverts commit 92aaf03a787fc37810c07a1f8605fc4f1bb73c29.
Bump to allow any highline version in the > 1.6.18 & < 1.7.x range

Fixes #3870
Fix issue where Product#set_property was causing an undefined method with spree_i18n

Fixes spree/spree_i18n#301

Conflicts:
	core/app/models/spree/product.rb