Merge pull request #5101 from themetric/fix-api-custom-template

add missing respond_with to some API controllers and add tests
Merge pull request #4844 from woboinc/bugfix/avoid_name_clashing

Avoid name clashing when including modules
Conflicts:
	core/app/models/spree/order.rb
add validation to verify that count_on_hand of backorderable should not go negative if it is not backorderable

Fixes #3808
add a before_transition to verify if order is resumed only if there are no insufficient stock lines
Fixes #3819

Conflicts:
	core/app/models/spree/order/checkout.rb
Fix API::Orders#create  for admins.