### What is this PR for?
Add HTTP client to elasticsearch interpreter.
### What type of PR is it?
Feature
### Todos
* [X] - Source code
* [X] - Tests
* [X] - License
* [X] - Docs
### What is the Jira issue?
https://issues.apache.org/jira/browse/ZEPPELIN-1821
### How should this be tested?
* Start an Elasticsearch node
* Configure the elasticsearch interpreter to use http
* Create queries in a note using elasticsearch
### Screenshots (if appropriate)
### Questions:
* Does the licenses files need update? Yes
* Is there breaking changes for older versions? No
* Does this needs documentation? Yes
Author: Bruno Bonnin <bbonnin@gmail.com>
Author: Bruno Bonnin <bruno.bonnin@myscript.com>
Closes#1902 from bbonnin/master and squashes the following commits:
f5a539e [Bruno Bonnin] Remove commented code lines
86153a8 [Bruno Bonnin] Merge remote-tracking branch 'upstream/master'
2e1bbbd [Bruno Bonnin] Merge remote-tracking branch 'upstream/master'
19e888e [Bruno Bonnin] Remove bad code in test
523d155 [Bruno Bonnin] Replace Java 8 methods
6bcf369 [Bruno Bonnin] Fix issue with id containing special chars (/, #)
4e9812e [Bruno Bonnin] Merge elasticsearch/pom.xml
5a96ae0 [Bruno Bonnin] Merge branch 'master' into master
e2365fb [Bruno Bonnin] Update elasticsearch/pom.xml
28b9805 [Bruno Bonnin] Update img
549db39 [Bruno Bonnin] Add HTTP client to elasticsearch interpreter
f4c5ac3 [Bruno Bonnin] HTTP-based Elasticsearch client
e763b3bf3e