Add default site customization pages

From now on these static pages:

`/privacy'
`/conditions'
`/accesibility'
`/help/faq'
`/welcome'

have been moved to the DB and can be modified easily by any
administrator in `/admin/site_customization/pages'

db/seeds.rb

@@ -126,3 +126,6 @@ WebSection.create(name: "debates")
 WebSection.create(name: "proposals")
 WebSection.create(name: "budgets")
 WebSection.create(name: "help_page")
+
+# Default custom pages
+load Rails.root.join("db", "pages.rb")