Add spec for updating version.
add table name for order/line_item association
fixes #5531
refactor code to follow DRY in zone model
fixes #5532
Update generated robots.txt
fixes #5533
Removes redundant closing li
fixes #5535
Make email field in admin orders#index link to the customer's account page
fixes #5539
Fix optimistic lock to not revert incremented version.

Conflicts:
	frontend/spec/controllers/spree/checkout_controller_spec.rb
	frontend/spec/controllers/spree/checkout_controller_with_views_spec.rb