old_contents: from changes.api.serializer import Serializer, register
  from changes.models.repository import Repository, RepositoryBackend
  
  
  @register(Repository)
  class RepositorySerializer(Serializer):
      def serialize(self, instance, attrs):
          return {
              'id': instance.id.hex,
              'url': instance.url,
              'backend': instance.backend,
          }
  
  
  @register(RepositoryBackend)
  class RepositoryBackendSerializer(Serializer):
      def serialize(self, instance, attrs):
          return {
              'id': instance.name,
              'name': unicode(instance),
          }
  
new_contents: from changes.api.serializer import Serializer, register
  from changes.models.repository import Repository, RepositoryBackend
  
  
  @register(Repository)
  class RepositorySerializer(Serializer):
      def serialize(self, instance, attrs):
          return {
              'id': instance.id.hex,
              'url': instance.url,
              'backend': instance.backend,
              'dateCretaed': instance.date_created,
          }
  
  
  @register(RepositoryBackend)
  class RepositoryBackendSerializer(Serializer):
      def serialize(self, instance, attrs):
          return {
              'id': instance.name,
              'name': unicode(instance),
          }
  
subject: Add dateCreated to repository serializer