Need async version of ElasticClient.Bulk method #380
Description
Issue abpunt Bulk method.
http://nest.azurewebsites.net/core/bulk.html
I can found "IndexManyAsync" and "DeleteManyAsync" methods in API, but method "Bulk" has no async version (BulkAsync) and internally uses IConnection.PostSync method.
https://github.com/Mpdreamz/NEST/blob/master/src/Nest/ElasticClient-Bulk.cs
Please also add BulkAsync method to API.