Allow redirect to remote census configuration tab

Currently after each update of any Settings is redirected to the first
tab by default.
As this new tab remote_census_configuation has a lot of fields to fill
in it is a bit uncomfortable to have to go back to the tab after each
update.

- Add hidden field :tag to set current tag value
- After update add tag value to request.referer
- To avoid errors when partial call has not param :tag, add the "define?"
  method on hidden_field value.

spec/features/admin/settings_spec.rb

@@ -162,6 +162,39 @@ describe "Admin settings" do
       Setting["feature.remote_census"] = nil
     end
 
+    scenario "Should redirect to #tab-remote-census-configuration after update any remote census setting", :js do
+      setting_remote_census = create(:setting, key: "remote_census.general.any_remote_census_general_setting")
+      Setting["feature.remote_census"] = true
+      admin = create(:administrator).user
+      login_as(admin)
+      visit admin_settings_path
+      find("#remote-census-tab").click
+
+      within("#edit_setting_#{setting_remote_census.id}") do
+        fill_in "setting_#{setting_remote_census.id}", with: "New value"
+        click_button "Update"
+      end
+
+      expect(page).to have_current_path(admin_settings_path)
+      expect(page).to have_css("div#tab-remote-census-configuration.is-active")
+      Setting["feature.remote_census"] = nil
+    end
+
+    scenario "Should not redirect to #tab-remote-census-configuration after do not update any remote census setting", :js do
+      admin = create(:administrator).user
+      login_as(admin)
+      visit admin_settings_path
+
+      within("#edit_setting_#{@setting1.id}") do
+        fill_in "setting_#{@setting1.id}", with: "New value"
+        click_button "Update"
+      end
+
+      expect(page).to have_current_path(admin_settings_path)
+      expect(page).to have_css("div#tab-configuration.is-active")
+      expect(page).not_to have_css("div#tab-remote-census-configuration.is-active")
+    end
+
   end
 
   describe "Skip verification" do