Refactored Core Order Checkout

Removed temp variables

Added tests to (remove|find)_transition

Added defensive programming approach into find_transition

Fixes #3630
Use delete_all to destroy all related product properties when deleting a property

Fixes #3610
Add sample gem to travis config.
initial port from 1-3-stable of spree order import api, updated for stock and adjustment states

Fixes #3617
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

Conflicts:
	backend/app/views/spree/admin/orders/customer_details/_form.html.erb
	backend/app/views/spree/admin/products/stock.html.erb
Fix conflict.
Bump aws-sdk to fix an s3 timeout error during pre processing. https://github.com/aws/aws-sdk-ruby/issues/241
Misc layout fixes for shipping and stock pages.

Conflicts:
	backend/app/views/spree/admin/stock_transfers/show.html.erb
Update aws-sdk and activemerchant to deal with nokogiri restrictions. Fixes #3625
Lets not run ci against sqlite3 to speed up travis builds by focusing on production databases.
[backend] Consistent no resource found. Fixes #3607
Set promotion rules before app initializer

And add a check in Promotion::Rules::User so associations are only
loaded once the app has set Spree.user_class. That allow users to set
their promotions rules on the spree.rb initializer again. e.g.

    Rails.application.config.spree.promotions.rules = [Spree::Promotion::Rules::Product]

Fixes #3599

Conflicts:
	core/app/models/spree/promotion/rules/user.rb
Fix deleting of images. Fixes #3562
Remove unused filter.
Grab deleted variants from a inventory unit

Needed after paranoia gem introduced a default_scope in variant model

Fixes #3628
Fetch active variant only in order import through api

Fixes #3647
standardized address attributes in api_helpers

Fixes #3646
adds awesome nested sets's 'depth' field in taxons

Fixes #3634
Cleanup Zone Editing

Fixes #3631