Looking up stock location by the admin name as well

fixes #5484
Add spec for looking up stock location by admin name.
Remove spec invalidated by https://github.com/spree/spree/commit/a13524a6cfd363c441ff1607a584a3be07e1124f now creating shipments.
Do not allow leading or trailing dot(.) in the first part of email address

Add rspec for email validator

Fixes #5483
Simplify set_current_order. Fixes #5382
Search for guest order first before running Order.new

Fixes #5441
Add inverse_of for more associations involved in cart processing
Fixes #5488
Loosen kaminari dep. Fixes #5486
Fix guides links.
remove extra dependent destroy
fixes #5492
Fixes messaging after applying coupon code promo with CreateLineItems action. Fixes #4697

Conflicts:
	core/lib/spree/testing_support/factories/order_factory.rb
	core/lib/spree/testing_support/factories/promotion_factory.rb
	core/spec/models/spree/promotion_handler/coupon_spec.rb
Refactor Spree::ProductHelper#variant_price_diff

* Change the logic of the code to make it easier for the next
  commit.
* Remove duplicate code from the HTML generation.

Change #variant_price_diff to handle when the product amount is nil

Fixes #5493
Allow order admin search via sku

remove white space

switch from expect to allow

fixes #5494
Add required attributes to required product admin form fields

* Adjust spec example inputs to allow submit with that restrictions.

fixes #5496
make bogus gateway match actual gateways. ie. don't assign profile id for failed payments

fix handling of retry payments and multiple payments

fixes #5499
Fix displaying product & taxon names when meta_title present.

Fixes #5502
Fixes #5501
Depend on factory_girl_rails 4.5.0
We need to be more restrictive with factory girl updates.
Implement a state lock version to prevent race conditions in checkout controller. refs #4190

Fix broken specs.

Add regression test for state lock version. Fixes #4190
Add circle CI setup

fixes #5506