- Fix unmounting select2 component

- Fix subjects of welcome and notification newsletters
- Remove debugging statements

assets/js/src/form/fields/selection.jsx

@@ -30,6 +30,9 @@ function(
           .trigger('change');
       }
     },
+    componentWillUnmount: function() {
+      jQuery('#'+this.refs.select.id).select2('destroy');
+    },
     setupSelect2: function() {
       if(
           !this.props.field.multiple
@@ -161,4 +164,4 @@ function(
   });
 
   return Selection;
-});
+});