Restore old pagination API for products

It's still used by the inventory page. This is an easy fix that I can
deploy without risk. A rewrite of the inventory pagination should
follow.

app/controllers/api/products_controller.rb

@@ -127,6 +127,9 @@ module Api
 
       render text: {
         products: serializer,
+        # This line is used by the PagedFetcher JS service (inventory).
+        pages: products.num_pages,
+        # This hash is used by the BulkProducts JS service.
         pagination: pagination_data(products)
       }.to_json
     end

spec/features/admin/inventory_spec.rb

@@ -0,0 +1,34 @@
+require "spec_helper"
+
+feature "Managing inventory", js: true do
+  include AdminHelper
+  include AuthenticationWorkflow
+  include WebHelper
+
+  it "shows more than 100 products" do
+    supplier = create(:supplier_enterprise, sells: "own")
+    inventory_items = (1..101).map do
+      product = create(:simple_product, supplier: supplier)
+      InventoryItem.create!(
+        enterprise: supplier,
+        variant: product.variants.first,
+        visible: true
+      )
+    end
+    first_variant = inventory_items.first.variant
+    last_variant = inventory_items.last.variant
+    first_variant.product.update_attributes!(name: "A First Product")
+    last_variant.product.update_attributes!(name: "Z Last Product")
+    quick_login_as supplier.users.first
+    visit admin_inventory_path
+
+    expect(page).to have_text first_variant.name
+    expect(page).to have_selector "tr.product", count: 10
+    expect(page).to have_button "Show more"
+    expect(page).to have_button "Show all (91  More)"
+
+    click_button "Show all (91  More)"
+    expect(page).to have_selector "tr.product", count: 101
+    expect(page).to have_text last_variant.name
+  end
+end