Change title when navigating to new product page

We navigate to it by replacing the content of the page through an ajax
call, so we also need change the section title with JS.

app/views/spree/admin/products/new.js.erb

@@ -0,0 +1,12 @@
+<%# This chunk is just a copy of Spree's core/app/views/spree/admin/products/new.js.erb %>
+$("#new_product").html('<%= escape_javascript(render :template => "spree/admin/products/new", :formats => [:html], :handlers => [:erb]) %>');
+handle_date_picker_fields();
+<% unless Rails.env.test? %>
+  $('.select2').select2();
+<% end %>
+$("#table-filter").hide();
+$("#admin_new_product").parent().hide();
+
+<%# We need to replace the page's title as well. We're navigating to a new page
+  although through ajax %>
+$('#content-header .page-title').html('<%= t('.title') %>');

config/locales/en.yml

@@ -2056,6 +2056,8 @@ Please follow the instructions there to make your enterprise visible on the Open
             other: "You have %{count} active order cycles."
           manage_order_cycles: "MANAGE ORDER CYCLES"
       products:
+        new:
+          title: 'New Product'
         unit_name_placeholder: 'eg. bunches'
         bulk_edit:
           header: