Update hub links to wombat
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.
Update index icons
Merge pull request #5509 from devilcoders/wombat_updates

Docs updates to include wombat
Add circle CI setup

fixes #5506
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
Not every payment method has to handle cancel

according to these two issues
https://github.com/spree/spree/issues/5307
https://github.com/netguru/spree_payu_integration/issues/5
I believe we has to check if cancel method is available before call it.
raise error if payment_method sub-class doesn't override cancel

fixes #5495
remove extra dependent destroy from variants
fixes #5511
Merge branch 'master' of https://github.com/spree/spree