Enable side blocks on product catalog

Also adds the ProductCategoriesBlock to list the catalog anywhere.

ActionItem896
Adds configuration for products per page on catalog

related to ActionItem896
Product Catalog and Product Categories Block styles

ActionItem896
Confirm if env templates are set as template

Adds "if <profile>.is_template" to <profile>_template methods.
List root product categories if no sub-categories

ProductCategoriesBlock will be never empty
ActionItem896
Add ProductCategoriesBlock to default enterprise creation

ActionItem896
Add manage products button to product catalog

ActionItem896
Migration to add ProductCategoriesBlock to all enterprises

ActionItem896
Test CatalogHelper

ActionItem896
Clone blocks
Better support for plugins migrations
Add STI, serialized field and rename enterprise_id
Add archived field to products
Add button to delete content on edition
cms_controller: add test for mandatory fields in blog creation form

ActionItem2762
add the nokogiri gem as dependency

AI2762
application_helper: use Nokogiri in convert_macro() instead of Hpricot

AI2762
cms_controller_test: use assert_select instead of assert_tag in certain tests

AI2762

Sadly, there is no way to use :checked in the css-like selectors used by
assert_select, otherwise the new versions  would be really neat.
articles, profiles: stop using ajax for some logged-in stuff
Allow toggle of name uniqueness on subtypes