Delete by query feature- Graylog and Elasticsearch API

Add delete by query API to delete records according to user requirements. We can give below two options that will enhance removal records from Elasticsearch API.
1) Delete by Query from Graylog
2) Delete by Query from Elasticsearch API

## Why?
We can add delete by query feature to eliminate sensitive records from the user's environments in his own space.

Here is the ticket: https://support.graylog.com/#ticket/zoom/3853

## Your Environment

* Graylog Version:3.3.5
* Elasticsearch Version:
* MongoDB Version:
* Operating System:
* Browser version: