Force dateFormat to dd/mm/yyyy for all locales

To maintain consistency and the use of advanced search in the frontend,
we forced the expected date format for all languages. This is a temporary
solution that we should analyze in depth to allow different date formats
depending on the language in the filters.

app/assets/javascripts/advanced_search.js

@@ -25,6 +25,7 @@
       });
       $(".js-calendar-full").datepicker();
       $.datepicker.setDefaults($.datepicker.regional[locale]);
+      $.datepicker.setDefaults({ dateFormat: "dd/mm/yy" });
     },
     initialize: function() {
       App.AdvancedSearch.init_calendar();

spec/features/admin/banners_spec.rb

@@ -179,6 +179,17 @@ describe "Admin banners magement" do
     expect(page).not_to have_content "Wrong text"
   end
 
+  scenario "when change date field on edit banner page display expected format", :js do
+    banner = create(:banner)
+    visit edit_admin_banner_path(banner)
+
+    fill_in "Post started at", with: "20/02/2002"
+    find_field("Post started at").click
+    within(".ui-datepicker") { click_link "22" }
+
+    expect(page).to have_field "Post started at", with: "22/02/2002"
+  end
+
   scenario "Delete a banner" do
     create(:banner, title: "Ugly banner",
                     description: "Bad text",