Add assertion that index creation & deletion is acknowledged
Suggest should ignore empty shards
From #3469.
When running suggest on empty shards, it raises an error like:

```
"failures" : [ {
      "status" : 400,
      "reason" : "ElasticSearchIllegalArgumentException[generator field [title] doesn't exist]"
    } ]
```

We should ignore empty shards.

Closes #3473.
Fix typo
Added completion statistics to indices stats