initial port from 1-3-stable of spree order import api, updated for stock and adjustment states
Adds update_line_items
Updates the tests to expect to create! instead of create

[Fixes #3603]
Improve cart page rendering:
- Render line_items collection in partial rather than looping
over line_items and rendering the partial multiple times

Fix #3609
Set created_by for orders when associating with a user IF the created_by value is blank.  Add specs for both cases.

Fixes #3614
Ensure order is refreshed before returning json
Fixes outdate jQuery live.

Remove colons for label tags for consistency in layout.

Add missing required for field in prototypes form.

Fixes taxon form layout issues.

- Add JS function that update info tag when typing permalink.
- Add space to required (still form don't get validated).

Remove loose p-tag in taxonomies index page.

Nicer products stock delete icons.

It still need its own delete js even because rows are nested and don't
gets fully deleted.

Fixes wild placed sorting icons.

Misc table layout styling.

Fixes #3619
Allow users to dont split packages

By making the Packer know how to deal with an empty splitters array we
allow users to set

    Rails.application.config.spree.stock_splitters = []

in theirs apps so that packages will never be split

Fixes #3618
Introduce better approach for regenerating shipments

Instead of recreating shipments every time customers change order items
it only destroy shipments, if any exists, and put order state back into
address so users are forced to transition the order again from address
to delivery and still recreate shipments properly

Another minor change on CheckoutController was necessary. We need to run
`setup_for_current_state` only after all other checks are done. e.g.
authentication, valid order state. This is so that customer don't get
their items removed by the Differentiator. Current specs should cover
all possible scnearios I could think of.

Fixes #3497

Conflicts:
	api/spec/controllers/spree/api/orders_controller_spec.rb