[WIP] Delete all records matching a query

Sorry, I'm having a bit of trouble digging through the code.

I think that this basic structure is correct for adding this functionality, but I'm unsure what to write in the `update_delete_all` method. Should it update some flag in the `request_options` `hash_storage`?

After that, where is the code that actually sends the request to ES? Will need to have it check for the new delete flag and send a DELETE request if it is true.
This test is currently failing with this message:

```
Failure/Error: specify { expect { city.reset }.to update_index(city) }
     Elasticsearch::Transport::Transport::Errors::BadRequest:
       [400] {"_indices":{"cities":{"_shards":{"total":1,"successful":0,"failed":1,"failures":[{"index":"cities","shard":0,"reason":"RemoteTransportException[[node-2][inet[/10.5.21.204:9302]][deleteByQuery/shard]]; nested: QueryParsingException[[cities] Required query is missing]; "}]}}}}
```

Maybe `reset` method is supposed to specify type somehow?
```ruby
def reset
  types(type_name).delete_all
  import
end
```