Alexander Lin 8f2882a442 Add _operation field to index, update, delete responses
Performing the bulk request shown in #19267 now results in the following:
```
{"_index":"test","_type":"test","_id":"1","_version":1,"_operation":"create","forced_refresh":false,"_shards":{"total":2,"successful":1,"failed":0},"status":201}
{"_index":"test","_type":"test","_id":"1","_version":1,"_operation":"noop","forced_refresh":false,"_shards":{"total":2,"successful":1,"failed":0},"status":200}
```
2016-07-26 11:16:19 -04:00
..
2016-06-24 22:03:03 -07:00
2014-11-08 13:55:23 +01:00