Raise an error if no unprocessed payments.

Fixes #5436

/cc @athal7 This breaks an exchanges rake task spec spec.
I spent a bunch of time trying to make it work right,
but haven't figure out proper way to do it.  It appears the while order.next
loop completes order because of default credit card bug.  Basically need a solution
to: Refs #5327

Conflicts:
	core/app/models/spree/order/payments.rb
	core/spec/models/spree/order/payment_spec.rb
Deleted the continue button from adjustment index

On the adjustment index (in the admin) was a continue button.
The button only shows up on this page, it's a leftover from the old 'manual add an order' proces in the admin.

I deleted it.

Fixes #5395
Regression spec for 'stack level too deep' #5384

Fixes #5384
Add in fix from @andrzejpolis Fixes #5384 Fixes #5386
Fix example to contain expectation
Fixes #5449
allow guests to use the payments api for their orders
Fixes #5450
Improve localization of stock_locations/_form
Fixes #5454
Fix factories to generate unique SKUs

* Choosing random SKUs even from a high range can yield duplicates
  resulting in build failures.
* Kernel.rand(9999) was definitively never a good choice due the
  birthday paradoxon lets manifest a duplicate quite often
* Uses sequencially generated SKUs defined from a single shared and
  reusable generator.

Fixes #5452
Update dependencies

* updated kaminari, cancancan and Ransack
* fix product admin page:
  delete 'deleted_at_null' from the searchg query hash as now ransack behaves
  property and won't include products with null delete_at value

Fixes #5455

Conflicts:
	core/spree_core.gemspec
Bump 2.3.4
Bump to next beta.
Make create endpoint require important params

bit of clean up on these tests, but no more after #create

Fixes #5458

Conflicts:
	api/app/controllers/spree/api/shipments_controller.rb
Moving admin index route to bottom of routes file to allow it to be overridden without breaking pagination on the orders page

Fixes #5461
Update jquery-ui-rails

Fixes #5462
Remove 'disabled' from inputs in payments

With the Aug 27 commit, a601035bd199a49f7f74ccf04ed0d889ca895f3e, the inputs under `.payment-method` are being disabled on line 15 but never correctly undisabled. This fixes that issue. Looks like it is affecting most branches.
fixes #5467
fix handling of credit cards expiring in current month
fixes #5468
Ignore guides.
Use Rails environments instead of DB configurations

In the admin forms for Spree::PaymentMethod and Spree::Tracker the collection used for the environment field is the database configuration keys. This is wrong and it becomes quite apparent in the case of applications that connect to more than one database. This commit replaces said collection with a collection of the available environment configurations in '/config/environments/'.

Closes #5170
Add issuestats badges.
Make best-promotion query more deterministic

Mostly for the benefit of the specs under MySQL.

This query was generating some sporadic spec failures for me when using MySQL as the database. This is because MySQL does not store fractional seconds so the "created_at" was sometimes the same value for two adjustments when running specs. And when created_at is identical the query below would actually pick the earlier adjustment instead of the more recent one.  Adding "id" as a fallback ordering fixes this problem and makes the behavior more deterministic.

The issue is reproduceable in postgres as well by using Timecop.

Fixes #4943