Avoid errors on select2 init using a name selector

Using a simple class selector to init select2 will throw an error if there is already an instance of select2 in the page with the same class selector.

backend/app/assets/javascripts/spree/backend/address_states.js

@@ -1,7 +1,7 @@
 window.update_state = function (region, done) {
   'use strict';
 
-  var country = $('span#' + region + 'country .select2').select2('val');
+  var country = $('span#' + region + 'country select.select2').select2('val');
   var state_select = $('span#' + region + 'state select.select2');
   var state_input = $('span#' + region + 'state input.state_name');
 

backend/app/assets/javascripts/spree/backend/images/index.js.coffee

@@ -10,4 +10,4 @@ $ ->
       url: @href
       success: (r) ->
         ($ '#images').html r
-        ($ '.select2').select2()
+        ($ 'select.select2').select2()

backend/app/views/spree/admin/products/new.js.erb

@@ -1,7 +1,7 @@
 $("#new_product_wrapper").html('<%= escape_javascript(render template: "spree/admin/products/new", formats: [:html], handlers: [:erb]) %>');
 handle_date_picker_fields();
 <% unless Rails.env.test? %>
-  $('.select2').select2();
+  $('select.select2').select2();
 <% end %>
 $("#table-filter").hide();
 $("#admin_new_product").parent().hide();

backend/app/views/spree/admin/promotion_actions/create.js.erb

@@ -2,12 +2,11 @@ $('#actions').append('<%= escape_javascript( render(partial: 'spree/admin/promot
 $('#actions .no-objects-found').hide();
 $(".variant_autocomplete").variantAutocomplete();
 //enable select2 functions for recently added box
-$('.type-select.select2').last().select2();
+$('select.type-select.select2').last().select2();
 
 initPromotionActions();
 
 
 $('#<%= dom_id @promotion_action %>').hide();
 $('#<%= dom_id @promotion_action %>').fadeIn();
 new Spree.CalculatorEditView({el: $('#<%= dom_id @promotion_action %> .js-calculator-fields')});
-

backend/app/views/spree/admin/stock_locations/_form.html.erb

@@ -114,7 +114,7 @@
 <% content_for :head do %>
   <%= javascript_tag do -%>
     $(document).ready(function(){
-      $('span#country .select2').on('change', function() { update_state(''); });
+      $('span#country select.select2').on('change', function() { update_state(''); });
     });
   <% end -%>
 <% end %>

backend/app/views/spree/admin/style_guide/topics/forms/_building_forms.html.erb

@@ -78,6 +78,6 @@
 
 <script>
 $(function(){
-  $('.select2').select2();
+  $('select.select2').select2();
 });
 </script>

backend/app/views/spree/admin/variants/new.js.erb

@@ -1,2 +1,2 @@
 $(".js-content-below-tabs").html('<%= escape_javascript(render template: 'spree/admin/variants/new', formats: [:html], handlers: [:erb]) %>');
-$(".js-content-below-tabs .select2").select2();
+$(".js-content-below-tabs select.select2").select2();