Changed Admin::OrdersController to Admin::Orders::CustomerDetailsController to try to get this
working with Spree 1.3
Removed the changes to the Admin::Orders::CustomerDetailsController because they no longer appear to
be necessary or useful in Spree 1.3.

In Spree 1.3, when you create a new order in the backend, it first shows you the Customer Details
page. At the top is a Customer Search field which lets you search for an existing customer. The
search results show the customer's address, and when you select a customer, it fills in the address
fields on the form from that user's address.

See also:
core/app/assets/javascripts/admin/checkouts/edit.js
core/app/views/spree/admin/search/users.rabl
core/spec/controllers/spree/admin/search_controller_spec.rb