Simplify handling of empty heading in discovery pane API

Just fall back to the addon name, don't include the author, it will
be part of the theme name already for some themes, that's how their
owner set it up.

src/olympia/discovery/serializers.py

@@ -28,10 +28,5 @@ class DiscoverySerializer(serializers.Serializer):
     def to_representation(self, instance):
         data = super(DiscoverySerializer, self).to_representation(instance)
         if data['heading'] is None:
-            if instance.addon.listed_authors:
-                data['heading'] = u'%s by %s' % (
-                    unicode(instance.addon.name),
-                    instance.addon.listed_authors[0].name)
-            else:
-                data['heading'] = unicode(instance.addon.name)
+            data['heading'] = unicode(instance.addon.name)
         return data

src/olympia/discovery/tests/test_views.py

@@ -38,8 +38,6 @@ class TestDiscoveryViewList(TestCase):
             if item.heading:
                 assert result['heading'] == item.heading
             else:
-                assert result['heading'] == u'%s by %s' % (
-                    unicode(addons[item.addon_id].name),
-                    addons[item.addon_id].listed_authors[0].name)
+                assert result['heading'] == unicode(addons[item.addon_id].name)
             assert result['description'] == item.description
-            assert result['current_version']
+            assert result['addon']['current_version']